What would cause one header tube to be hotter than the others? [Archive] - Team Camaro Tech

: What would cause one header tube to be hotter than the others?


mnm99
Apr 10th, 07, 03:26 PM
I took temps on all tubes after 10 min of running. Here's the numbers I got


278 (8) 268 (7)
370 (6) 250 (5)
238 (4) 230 (3)
200 (2) 198 (1)

As you can see it's cooler towards the front, That makes sense. What do you think about cylinder #6?

Note...All the ignition is good, plugs good, compression test good, Intake gasket good(changed)carb good (new), can't find vac leaks.

dawg
Apr 10th, 07, 03:29 PM
rejet to a higher jet in the carb I would think
im betting someone changed jets and got em all mixed up

Larger Dave
Apr 10th, 07, 04:31 PM
Don't know if I would rejet without first reading the plugs.

To answer your question; the reason one tube is hotter than another is because of a difference in fuel distribution between the cylinders. This is the reason Barry Grant introduced his new four shooter carb. And the reason dyno cells have thermocouples on every tube of the exhaust header. You can adjust the jetting to compensate, or go to two fours on a different manifold, or convert to port injection EFI as possible means of correcting the problem. Most don’t worry about it so long as it isn’t so lean as to make a tube glow red., and the motor pulls strong.


Larger Dave

zdld17
Apr 10th, 07, 04:32 PM
If this is on a dual plane manifold, put this in prespective with the distance of the carb and what ports are feeding what. Generally the ports that share one side of the carb that are furtherest, can get the hottest. IMO. But if you have a vacumn leak somewhere, this will also have impact. Think about it.

mnm99
Apr 10th, 07, 04:50 PM
rejet to a higher jet in the carb I would think
im betting someone changed jets and got em all mixed up


It's a brand new carb. I wouldn't think the jets ar mixed up. It only is on #6. If you have been reading this post.
http://www.camaros.net/forums/showthread.php?t=104084
You can see what I'm trying to find out.

mnm99
Apr 10th, 07, 04:53 PM
If this is on a dual plane manifold, put this in prespective with the distance of the carb and what ports are feeding what. Generally the ports that share one side of the carb that are furtherest, can get the hottest. IMO. But if you have a vacumn leak somewhere, this will also have impact. Think about it.

Yes it's a duel plane. But why would it only be on 1 cylinder? wouldn't it be on say #6 AND #5. I replaced the intake gasket already. I'll look for leaks AGAIN! Could anything with the valves do this?

Remember I have been trying to find a low RPM miss and a little loss of power.

JimM
Apr 10th, 07, 05:13 PM
ok... after re-reading the other post... it seems to make all the sense in the world that the high egt on 6 and the miss is related.

2 ways to prove it. Best way would be to hook it up to an old fashioned sun machine, the kind with the big osciloscope display? That will show in a heartbeat what is going on.

Shadetree way would be to remove (and ground out) each plug wire (one at a time) and verify all but # six gives you a new miss.

I was gonna say AH-HAH and blame the power brake booster, but that hooks into #8 so never mind.

So what causes a high EGT? Could be a lean misfire. Could also be burning fuel in the exhaust port.

Do you still have the issue where one idle screw will kil the motor but the other one won't?
As was said, that is a big clue.

What does your vacaum guage needle look like?
Does the needle flutter?

Still bothering me that the compression is perfect on this engine.

With each primary feeding 4 cylinders, it's hard to blame this on carb, but the ignition had been ruled out.

Think I'll go help the wife get dinner on the table, and ponder this some more later.

mnm99
Apr 10th, 07, 05:20 PM
ok... after re-reading the other post... it seems to make all the sense in the world that the high egt on 6 and the miss is related.

2 ways to prove it. Best way would be to hook it up to an old fashioned sun machine, the kind with the big osciloscope display? That will show in a heartbeat what is going on.

Shadetree way would be to remove (and ground out) each plug wire (one at a time) and verify all but # six gives you a new miss.

I was gonna say AH-HAH and blame the power brake booster, but that hooks into #8 so never mind.

So what causes a high EGT? Could be a lean misfire. Could also be burning fuel in the exhaust port.

Do you still have the issue where one idle screw will kil the motor but the other one won't?
As was said, that is a big clue.

What does your vacaum guage needle look like?
Does the needle flutter?

Still bothering me that the compression is perfect on this engine.

With each primary feeding 4 cylinders, it's hard to blame this on carb, but the ignition had been ruled out.

Think I'll go help the wife get dinner on the table, and ponder this some more later.

I'll try to awnser best as possible..
-Idle screws work right, Both will kill the motor one at a time
- Vac gauge is around 11 inches ,slight flutter maybe 1/2 inch. Prob cam related.
- Grounded out wires and they all sound the same.

Also I am noticeing , I may be going crazy because of all the test I've done, but right around that cylinder I hear a clacking sound. Not a loose rocker sound or a rod knock, kinda K K K K , EVER SO SLIGHT. I tried putting my trusty sprinkler hose around and I couldn't hear anything. Maybe I'll pull the cover again and take a look.

sleeper69
Apr 10th, 07, 05:23 PM
Do you have a vacuum fitting on that runner of the intake? If so chances are there is a vacuum leak somewhere between the fitting and the end of whatever is hooked to it? Maybe a brake booster?

mnm99
Apr 10th, 07, 05:29 PM
Do you have a vacuum fitting on that runner of the intake? If so chances are there is a vacuum leak somewhere between the fitting and the end of whatever is hooked to it? Maybe a brake booster?


No, nothing

sleeper69
Apr 10th, 07, 05:33 PM
You mentioned a flutter with the vacuum gauge? Any chance of a broken valve spring?

zdld17
Apr 10th, 07, 05:48 PM
Yes it's a duel plane. But why would it only be on 1 cylinder? wouldn't it be on say #6 AND #5. I replaced the intake gasket already. I'll look for leaks AGAIN! Could anything with the valves do this?

Remember I have been trying to find a low RPM miss and a little loss of power.

Manifold I am looking at, 5 & 6 do not come off same plane level. With a plenum divider and two front idle circuits in front, thats one circuit out of two , that will have to feed 4 clys, those clys closest to idle circuits get the strongest vacumn signal, Cly 5 is furthest away on top plane. On lower plane #6 is even further and gets the weaker vacumn signal as being further away than 5 coming from a higher plane. .
The port furtherest away will prolly get less atomized fuel or it will lay on the floor of the manifold thus not have very much velocity to get to cly thus being somewhat lean? Wonder what happens to temps when rpm is set up higher? Would spark plug indexing help here? You must be generating more heat for some reason and being lean is my first guess.
I would look at richening up the idle circuits. . Perhaps you also have less cly leakage on that cly also, thus running a higher dynamic compression? Could a valve be too tight or loose? What PV are you running? What Carb?

Joe Harrison
Apr 10th, 07, 05:52 PM
Also possible sticking valve from heat? Intake could also still be the culprit. Plug off all vacuum to the engine so nothing is drawing vacuum to anyplace.

Plug breathers with a rag. Stick a can of cab cleaner with the red small tube into one of the closed off breathers and start spraying. If you get an increase idle just as you would looking around the base of the carb or hoses etc you have an internal vacuum leak. This leak will most likely be your intake and #6 can be a trouble to seal due to thin seal at the FWD edge.

If you find an internal you might also try spraying around the intake at all sealing areas that are external locations after trying this to see if you have air leaking from anyplace else. Make sure you have the breather you were spraying into covered and plugged and everything else plugged.

On you dual plane intake you could pressurize you engine and see which side of the intake air comes from. I would not use more than about 10 to 15 PSI. I have done this before but do this part at you own risk. Rings and seating can be affected.

Joe

mnm99
Apr 10th, 07, 05:55 PM
Manifold I am looking at, 5 & 6 do not come off same plane level. With a plenum divider and two front idle circuits in front, thats one circuit out of two , that will have to feed 4 clys, those clys closest to idle circuits get the strongest vacumn signal, Cly 5 is furthest away on top plane. On lower plane #6 is even further and gets the weaker vacumn signal as being further away than 5 coming from a higher plane. .
The port furtherest away will prolly get less atomized fuel or it will lay on the floor of the manifold thus not have very much velocity to get to cly thus being somewhat lean? Wonder what happens to temps when rpm is set up higher? Would spark plug indexing help here? You must be generating more heat for some reason and being lean is my first guess.
I would look at richening up the idle circuits. . Perhaps you also have less cly leakage on that cly also, thus running a higher dynamic compression? Could a valve be too tight or loose? What PV are you running? What Carb?

New holley 670 Avenger. 6.5 power valve. I'll double check the valves tommorrow. I readjusted them 3 times in this whole process. The idle/miss never changed.

When I had the RPM set at 1500 for 5 min that cylinder was the hotest also. I didn't write down the numbers but I think they were all in the high 300's and that was in the 400's

dawg
Apr 10th, 07, 05:57 PM
ok your sure the carb is ok
next question is if its not the carb a vacum leak is possible on that intake runner.
I chased an internal leak to the intake manifold gasket that didnt seal on the underside of the intake causing the mixture to lean out that cylinder and make the noise you mentioed (somewhat).
the oil smelled a bit like gas in worse case senerio like mine was.
after 2 sets of gaskets i found the intake (which I bought at a swap meet as new) was the culprit and wasnt sealing due to improper torque sequence.
Im betting you have the same problem.
BTW just cuz the carb is new doesnt mean its good.
I returned a few NEW carbs for various problems

zdld17
Apr 10th, 07, 06:00 PM
Don't see anything wrong with your Holley unless one side is not delivering fuel or enuff of it. May try what Joe is talking about, I have heard this work more than once. Its hard to diagnose problems like this , 1500 miles away. Just got to check and recheck.

mnm99
Apr 10th, 07, 06:45 PM
ok your sure the carb is ok
next question is if its not the carb a vacum leak is possible on that intake runner.
I chased an internal leak to the intake manifold gasket that didnt seal on the underside of the intake causing the mixture to lean out that cylinder and make the noise you mentioed (somewhat).
the oil smelled a bit like gas in worse case senerio like mine was.
after 2 sets of gaskets i found the intake (which I bought at a swap meet as new) was the culprit and wasnt sealing due to improper torque sequence.
Im betting you have the same problem.
BTW just cuz the carb is new doesnt mean its good.
I returned a few NEW carbs for various problems

I hear everything your saying. If you read my other thread this happend all of a sudden. I replaced the intake gaskets once and made sure they sealed GOOD, just like I did the first time. I know what your saying,but I don't think it's my gaskets. Who knows. I really don't want to change them again.I torqed them correct in three stages. My old carb was the exact same way. Nothing changed with the new one.

77wolf10.85
Apr 10th, 07, 08:32 PM
I feel your pain.
Not trying to undermine any of the good advice anybody is giving you, but don't read too much into those exhaust temps.
I work on industrial V-12 and V-16 engines( from about 3000 to 10,000 cu in + ) that have pyrometers. You ignore the damthings until the engine has a monster load on it. Unless you have a dead hole. It's not uncommon for an idling engine to have 3-400 degrees difference between cylinders. It just means they aren't working yet. 1500 RPM fast idle temp test, no sorry, you still just barely have the throttle open. It might come around some, but I wouldn't expect it to be consistent yet.

A trick for detecting a sticking or burned intake valve is to shoot the temperature of the intake manifold runner to that cylinder. I guarantee it'll show.

I am, unfortunately, siding with the gentleman telling you to not expect your new carb to be a good carb. I once had a pretty strong stock 350 with an Edelbrock carb. Ran great but every 20 or 30,000 miles it would lose a little manifold vaccuum and get a little flutter in same. Drop from like 16" to shaky 12" if I remember right. Rebuild the carb, Good for another year or so. Never saw a damthing wrong with the carb. Got to where I just took it apart and blew air through all the passages to heal it.

Failing in that I would rip the intake and heads off and be done with it.

oger
Apr 10th, 07, 10:14 PM
Make sure you are getting a good read with the temp gun. They can be very tricky about paint etc.

ACEHAAG
Apr 11th, 07, 02:24 AM
Does your engine still have egr that may be sticking causing it to lean out cylender 6

mnm99
Apr 11th, 07, 05:02 AM
I feel your pain.
Not trying to undermine any of the good advice anybody is giving you, but don't read too much into those exhaust temps.
I work on industrial V-12 and V-16 engines( from about 3000 to 10,000 cu in + ) that have pyrometers. You ignore the damthings until the engine has a monster load on it. Unless you have a dead hole. It's not uncommon for an idling engine to have 3-400 degrees difference between cylinders. It just means they aren't working yet. 1500 RPM fast idle temp test, no sorry, you still just barely have the throttle open. It might come around some, but I wouldn't expect it to be consistent yet.

A trick for detecting a sticking or burned intake valve is to shoot the temperature of the intake manifold runner to that cylinder. I guarantee it'll show.

I am, unfortunately, siding with the gentleman telling you to not expect your new carb to be a good carb. I once had a pretty strong stock 350 with an Edelbrock carb. Ran great but every 20 or 30,000 miles it would lose a little manifold vaccuum and get a little flutter in same. Drop from like 16" to shaky 12" if I remember right. Rebuild the carb, Good for another year or so. Never saw a damthing wrong with the carb. Got to where I just took it apart and blew air through all the passages to heal it.

Failing in that I would rip the intake and heads off and be done with it.


Thanks for the advice. I will check the intake runner. What would it show? Lower or higher? As for the carb..I know I could have a bad one, but 2 in a row with the EXACT symptom? I took my first one apart and cleaned every nook and cranny. Put a new PV in it, new gaskets, verified it was straight, float level ect...Put it back on and same thing. Bought a new one same thing. I can't believe this could be it. Guess anything could happen at this point. I'm just not going out to buy ANOTHER carb again.

I'm getting real close to get a new set of heads and intake!!! It would kill me though if it was an ignition problem though. I did remove the entire MSD and put back my points and the problem was still there, so I don't think its the ignition. I did this twice also. I would like to get a leak down test first before I did the heads and also put it on the osciloscope like jim says first.

No, I have no EGR.

Everett#2390
Apr 11th, 07, 05:09 AM
With vacuum gauge hooked up, increase rpm to 3500 and recheck temps after you've verified gun works correct and the surface you're shooting on #6 is the same as the rest, i.e., no paint/rust.

Reason for the higher rpm is to get the carb into the main fuel circuit, off the idle circuit. Vacuum will go up and temp should become more even.

Now, if temp doesn't even out, then it might be a weak cylinder. Let the engine idle for a few minutes and if vacuum gauge still has a 1/2 inch flutter, and #6 comes back up in temp at idle, then I'd do a leakage test of the cylinder to get an idea of well it is sealing. If leakage test or compression test, shows good results, then I would look at the intake gasket, or as mentioned EGR valve area, or brake booster supply.

You have tighten the intake bolts again?
Do you use the manifold end seals between the block and manifold? Sometimes the end seals don't compress enough to allow the head surface to seal with the manifold and a leak on the crankcase side of the gasket can occur.

Good luck.

mnm99
Apr 11th, 07, 05:18 AM
With vacuum gauge hooked up, increase rpm to 3500 and recheck temps after you've verified gun works correct and the surface you're shooting on #6 is the same as the rest, i.e., no paint/rust.

Reason for the higher rpm is to get the carb into the main fuel circuit, off the idle circuit. Vacuum will go up and temp should become more even.

Now, if temp doesn't even out, then it might be a weak cylinder. Let the engine idle for a few minutes and if vacuum gauge still has a 1/2 inch flutter, and #6 comes back up in temp at idle, then I'd do a leakage test of the cylinder to get an idea of well it is sealing. If leakage test or compression test, shows good results, then I would look at the intake gasket, or as mentioned EGR valve area, or brake booster supply.

You have tighten the intake bolts again?
Do you use the manifold end seals between the block and manifold? Sometimes the end seals don't compress enough to allow the head surface to seal with the manifold and a leak on the crankcase side of the gasket can occur.

Good luck.


Ok, How long should I keep it at 3500? I'll check that. The compresson test I did came up with 162 on #6 , 160 on #4, 160 on #2 for instance. One of my friends at work who's a mechanic for my company said try a running compression test . So I did and got 90psi on #6, 90psi 0n #4. I was told compression tests arent that accurate. I have to find someone that could do a leak down test.

The headers are ceramic coated and clean.

I used silicone on the ends and a 1/16 bead around every port top and bottom. Torqed in correct order in 3 steps.

mnm99
Apr 11th, 07, 05:52 AM
$100 and a case of beer to the first one that can figure out my miss!:D

dawg
Apr 11th, 07, 07:19 AM
WOW:D someone called me a gentleman???
hmmm but why?

Everett#2390
Apr 11th, 07, 07:32 AM
Ok, How long should I keep it at 3500? I'll check that. About 15-30 seconds, or until the heat stabilizes.The compresson test I did came up with 162 on #6 , 160 on #4, 160 on #2 for instance. One of my friends at work who's a mechanic for my company said try a running compression test . So I did and got 90psi on #6, 90psi 0n #4. I was told compression tests arent that accurate.Explain the difference.90 PSI on 6 & 4 would indicate a blown head gasket between the two cylinders. I have to find someone that could do a leak down test.
The headers are ceramic coated and clean.
I used silicone on the ends and a 1/16 bead around every port top and bottom. Torqed in correct order in 3 steps.A cheap leak test would be to charge up the cylinder with shop air and measure the time the cylinder leaks to a certain level. Do the same to two other cylinders for comparision. They all should be within 10-15 seconds of each other, I would think.

Good shooting surface, all are the same. What about shooting the separate tubes in a different spot?

Good torque instructions. Still wouldn't be a bad idea to check bolt torque.
Using the end seals from the intake gasket set?

zdld17
Apr 11th, 07, 08:50 AM
We have a winner!

mnm99
Apr 11th, 07, 09:13 AM
About 15-30 seconds, or until the heat stabilizes.Explain the difference.90 PSI on 6 & 4 would indicate a blown head gasket between the two cylinders.A cheap leak test would be to charge up the cylinder with shop air and measure the time the cylinder leaks to a certain level. Do the same to two other cylinders for comparision. They all should be within 10-15 seconds of each other, I would think.

Good shooting surface, all are the same. What about shooting the separate tubes in a different spot?

Good torque instructions. Still wouldn't be a bad idea to check bolt torque.
Using the end seals from the intake gasket set?

Used silicone on end seals.

Torque is at 30lbs

I should have never posted the pressures. All cylinders were around 160psi just cranking and 90psi one at a time with the engine running. I was just giving a comparison to the next cylinder over. The compression is good, I did it twice. All around 160.

If the carb is good and there are no leaks intake or carb leaks. What in the head would cause this? I was told stuck valve? Valve not seating ect.... Can you explain?

mnm99
Apr 11th, 07, 09:18 AM
We have a winner!


No winner yet!

zdld17
Apr 11th, 07, 09:20 AM
No winner yet!

Dang, we were getting so close. Thought he said he got 90# on 6 & 4?

Maybe do as Everett mentioned, pull plugs on 6 & 4, make sure valves are closed, pressure one up, see if air is coming out the other?

mnm99
Apr 11th, 07, 09:55 AM
I'll try that. How do you hold the engine from turning when doing a leak down test? Anything over 40psi will start to turn it over.

Joe Harrison
Apr 11th, 07, 10:05 AM
No metion of checking for that internal vacume leak?
A silicone bead around your intake port might be a problem. Silicone will not seal very well at the intake ports. It does not stand up to Vacume very well when used in small quanitys as required for this seating. If alot is used, fuel will break it down and the excess can dislodge and become a problem. If you have a big hunk at #6 it could be breaking up your mixture into the port and cause puddling of the fuel at the bead sticking up. It is then getting a lean hit and when the fuel dumps over the silicone bead it gets a rich dump.

Back to the intake gasket. If oil is sucked up or the head surface dirty or oily at all it's going to leak. The oil gets sucked between the gasket and the silicone and it debonds and allows a leak. If you go back into to it or try the internal leak check method I post above the method below is how I put an intake on. My way is a proccess method that I have used for years and it's worked great for myself and others sufering from leaking intakes.

Use a product called Aviation Form A gasket from permatex. It comes in a bottle and has a brush attached to the cap. It really never gets dry to say. It stays somewhat sticky. It dries but not hard but hard enough to stay as a sealer between the two faying surfaces.

Use brake cleaner, not carb cleaner to clean all your surfaces. Carb cleaner leaves a residue and has some lubricant in it. Clean everything very well using new shop rags and spraying cleaner on the rag and cleaning the surfaces of the heads and intake. Also you manifold end seals.

Next use a very small small bead of silicone around your water ports on the head and intake manifold. Put you gasket up to see where it needs to be and like I said a very small bead is all that's needed. I like permatex ultra black BTW.

Next using the aviation and the attached brush. Brush the aviation around your intake ports on the heads and the intake. Let it get a little tacky, and put on a little more. You can tell when it covers the faying surface your going to seal. It may only take one coat. Do both the heads and the intake. Put your silicone bead on the manifold ends. Lay in you intake gaskets. Put a small bead on the manifold ends to cover the area where the gasket just went down on the manifold ends.

Take the intake and four intake bolts. Set the intake onto the engine as evenly as possible put don't push down, let it naturaly sit. Put the four bolts in the center four holes but don't tighten them to contact with the intake. Do the same with the rest of the bolts. starting with center start taking them down slowly following the torque pattern but do not torque them, you are only snuging them up. Follow this a few times. The manifold should be evenly seated in the heads. Now torque it down. Let it sit for about 2 or 3 minutes to allow squeeze out of the silicone and aviation between the two faying surfaces and for gasket compression. Re-torque it again and wait as above and re-torque one more time. After running it go over the pattern one more time after heating and cooling completly.

mnm99
Apr 11th, 07, 10:24 AM
I don't know what to say. I just replace the intake gaskets a week ago thinking that was the problem. I did it very carefully and cleaned everything real well and had the same exact problem. I'm not saying your wrong ,but I never had a problem the way I did it. I need to do a leak down test. Thanks for that info though.

Everett#2390
Apr 11th, 07, 10:32 AM
Rotaste the engine over by hand up to and maybe just past TDC of the compression stroke. Leave the flex handle and socket on the crankshaft bolt and let it rest on the frame to hold the engine from spinning.

After this, you should be able to inject 100 PSI shop air into the cylinder(s) and not worry about engine turning. but 40 PSI is good to start. More is better.

Valve lift, or lack of, is a good problem for a leaner cylinder, along with a little 'tic', 'tic', 'tic'. Or a lifter not pumping up due to low oil pressure, a bad check valve in the lifter, or dirt in the lifter body oil keeping the check valve open. Lifter collapses, reduces valve lift and tics.

You mentioned engine has low vacuum at idle. The PCV valve rattles at the same time. You may have to exchange it for a PCV valve from a Z/28, as they had reduced vacuum. The valve you have now is for a stock-cammed engine with higher vacuum and has a different spring.

I haven't been too keen of using RTV on the intake ports. But I'd still hand torque the manifold bolts working from the i8nside out.

I'd probably go and swap a plug with another cylinder then do another plug wire just to be sure.

A sticking valve and an unseated valve would still cause both issues of fluttering gauge and lean cylinder.

What happens when you spray WD40 into the carb while running?

mnm99
Apr 11th, 07, 11:17 AM
Rotaste the engine over by hand up to and maybe just past TDC of the compression stroke. Leave the flex handle and socket on the crankshaft bolt and let it rest on the frame to hold the engine from spinning.

After this, you should be able to inject 100 PSI shop air into the cylinder(s) and not worry about engine turning. but 40 PSI is good to start. More is better.

Valve lift, or lack of, is a good problem for a leaner cylinder, along with a little 'tic', 'tic', 'tic'. Or a lifter not pumping up due to low oil pressure, a bad check valve in the lifter, or dirt in the lifter body oil keeping the check valve open. Lifter collapses, reduces valve lift and tics.

You mentioned engine has low vacuum at idle. The PCV valve rattles at the same time. You may have to exchange it for a PCV valve from a Z/28, as they had reduced vacuum. The valve you have now is for a stock-cammed engine with higher vacuum and has a different spring.

I haven't been too keen of using RTV on the intake ports. But I'd still hand torque the manifold bolts working from the i8nside out.

I'd probably go and swap a plug with another cylinder then do another plug wire just to be sure.

A sticking valve and an unseated valve would still cause both issues of fluttering gauge and lean cylinder.

What happens when you spray WD40 into the carb while running?

I haven't tried the WD40. I did put my hand over the carb and the idle did go up. What would happen with WD40?

Oil pressure is 65 cold and 30 warm.

I'll try the socket thing.

zdld17
Apr 11th, 07, 11:32 AM
Correct me, if piston is just past the compression stroke on the down side, putting air in the cly, and the socket on the harmonic bal bolt, the rotation will still occur? And loosen the bolt? Wouldn't it be just as easy to put piston all way down and make sure valves are closed? Been hit with a breakover before. :eek:

hand over carb air horn and idle did go up? you have a vac leak somewhere.

Joe Harrison
Apr 11th, 07, 11:39 AM
I would still check for that internal vacume leak. It's easy to do and will eliminate one piece of the puzzle. You could do everything right on intake install on a SBC and still have one leak.

Is your intake a cast iron one?

If it's a cast iron intake the can be cracked at the exuhaust cross-over passage into the plenum bottom and the vacume leak will be right at the bottom. Only true way to check this is remove the intake, remove the sheet metal plate clean and mag the intake. I have seen some that are so bad you can look down from the carb and see the crack or cracks.

Internal test I have above can also confirm this. You have to spray alot though for it to suck up through the plate,carbon build up then through the crack.

Joe

Joe Harrison
Apr 11th, 07, 11:42 AM
hand over carb air horn and idle did go up? you have a vac leak somewhere.

That's what my bet would be on. Vacume leaks SUCK :yes:

Joe

Everett#2390
Apr 11th, 07, 12:33 PM
Correct me, if piston is just past the compression stroke on the down side, putting air in the cly, and the socket on the harmonic bal bolt, the rotation will still occur? And loosen the bolt? Wouldn't it be just as easy to put piston all way down and make sure valves are closed? Been hit with a breakover before. A hundred pounds of shop air isn't enough to loosen the bolt and I'm only talking of maybe a few degrees passed TDC any way.

The stroke of the pressurized cylinder is less than the length (stroke) of the flex handle.

The WD40 would richen the fuel/air mixture, denoting a vacuum leak.

And yes, if rpms go up with hand over carb, there is a vacuum leak. Vacuum leaks do suck!

lortsie
Apr 11th, 07, 12:36 PM
If it's a cast iron intake the can be cracked at the exuhaust cross-over passage into the plenum bottom and the vacume leak will be right at the bottom. Only true way to check this is remove the intake, remove the sheet metal plate clean and mag the intake.

I think I saw somewhere that somebody sells a home liquid UV crack detection kit. Anywone know any more about that? Sounds like a bear of a problem. :confused:

mnm99
Apr 11th, 07, 03:06 PM
Update. I tried the plugging all vac ports and spraying car cleaner in the valve covers and still nothing. I sprayed carb cleaner around the entire intake also.

I ran it at 2500 rpm for 30 sec and cylinder #6 came out 250* higher than the highest one. All were around 400* and cylinder 6 was 650*.

I did a sort of leak down test putting 50psi in the cylinder and checking in the carb and exhaust with a tube to my ear and didn't hear anything. I did hear air leaking but couldn't find where.

Could a blown head gasket do this?

lortsie
Apr 11th, 07, 03:12 PM
I think a mechanical problem in the head like others have mentioned is more likely. Stuck valve, broken spring, etc. Good chance to have them ported :)

Also one thing to consider other than AF mix is cooling - there may be an issue with coolant flow around that cylinder. Just a thought.

mnm99
Apr 11th, 07, 03:52 PM
I think a mechanical problem in the head like others have mentioned is more likely. Stuck valve, broken spring, etc. Good chance to have them ported :)

Also one thing to consider other than AF mix is cooling - there may be an issue with coolant flow around that cylinder. Just a thought.


I didn't notice a broken spring or a stuck valve. They go up and down just as much as the others.

If it was a head gasket I don't see any smoke or bubbles in the rad. I would just get a set of new heads if it's the gasket or head. I just want to make sure it's one of them and not a Cam or a piston. Whats really weird is my compression!!!!
#1 = 160
#3 = 162
#5 = 162
#7 = 162
#2 = 157
#4 = 160
#6 = 160
#8 = 157

Temps
278 (8) 268 (7)
370 (6) 250 (5)
238 (4) 230 (3)
200 (2) 198 (1)

Everett#2390
Apr 11th, 07, 03:53 PM
Update. I did hear air leaking but couldn't find where. Could a blown head gasket do this?If suspecting head gasket, one place to look is in radiator coolant for bubbles while suppying air. The other place would be to listen and or feel at oil fill cap, or place hand(s) over all available places of crankcase entry, and tape oil dipstick tube or cork it, and feel for build-up of pressure after 30 seconds to a minute. Or another cylinder spark plug hole?

If you need a fender roller for tire clearance, use a baseball bat and roll it with the tire and roll the car.

Joe Harrison
Apr 11th, 07, 05:12 PM
Here is a post with an excellent idea!! I have thought of doing this but never have. I tried with a mity vac hand pump and in 2 minutes no luck and a sore hand....lol http://www.camaros.net/forums/showthread.php?t=105570

Cam wise you could still have good compression and have a worn lobe. My 327 will attest to this and it had a miss I chased for while as you are. Engine still ran excellent. It ran very well but had an idle miss put into RMP it was hardly noticable. It was also hot shooting it. Plug would always show leaner than others. I figured it to be leaking guides. After tearing it down it was a cam problem. It also had some pretty loose guides.

Joe

mnm99
Apr 11th, 07, 05:21 PM
Thanks.. I did sort of a leak down test on 2,4,6,8 putting 60psi in with the piston at TDC, both valves closed. The only place I heard air was the dip stick tube. The same ammount on all cylinders.

As for the cam. I guess the only way I would tell if it was a lobe without tearing it down would be with a dial tester right?

zdld17
Apr 11th, 07, 06:16 PM
You keep going back to my second to last thought but I figured you checked this. I was thinking of a blown head gasket, between 4 & 6, Thats why I asked, if when you pressured either, did you notice any pressure build up on the suspected clyinder. 4 to 6 or 6 to 4. but when you said the motor speeds up when you choke off inlet air, that throws me off , again.

Checking cam lift at the rocker with a dial indicator or something percise, is one way to check cam lobes.

JimM
Apr 11th, 07, 06:19 PM
As for the cam. I guess the only way I would tell if it was a lobe without tearing it down would be with a dial tester right?
Right.

This engine is tight. The compression test is within a couple percent, leakdown is ok we think.

EGT at 3500 shows similar results to first test. #6 IS hot, much hotter than the others.

This ain't a carb problem, carb ain't gonna effect one and only one cylinder no way no how.

Not ignition either. Replaced the whole system, no change.

I'm gonna go out on a limb and say the intake gasket's not it either. I would not use silicone around the ports myself, I use copper spray, but still, was same before and after, no way it went back together the same bad way it was before it came apart.

Vacaum gauge shows a fluctuation. That and the hot egt on #6 are all we got.

This happened suddenly.

All that's left is the cam (flat exhaust lobe on #6?), possibly a collapsed lifter, or a yet undiscivered vacaum leak, close to the valve in the #6 intake port. Does this thing have pressed or screw in studs? Is a pressed stud pulling out, or a screw in stud loose? MAybe a real bad valve guide, tho it would seem weird to lose only one out of 16?

Everett#2390
Apr 11th, 07, 06:30 PM
All that's left is the cam (flat exhaust lobe on #6?), possibly a collapsed lifter, or a yet undiscivered vacaum leak, close to the valve in the #6 intake port. Does this thing have pressed or screw in studs? Is a pressed stud pulling out, or a screw in stud loose? MAybe a real bad valve guide, tho it would seem weird to lose only one out of 16?Agree with all said. But, with a pulled stud or unscrewed stud, rocker noise due to loose lash would be very noticeable. mnm99 didn't mention any noise other than a "soft/light" tic at idle.

I do agree it could be a worn cam lobe, unless mnm's been adjusting the valves and not noticing a loose valve/rocker arm.

mnm99
Apr 11th, 07, 06:32 PM
Right.

This engine is tight. The compression test is within a couple percent, leakdown is ok we think.

EGT at 3500 shows similar results to first test. #6 IS hot, much hotter than the others.

This ain't a carb problem, carb ain't gonna effect one and only one cylinder no way no how.

Not ignition either. Replaced the whole system, no change.

I'm gonna go out on a limb and say the intake gasket's not it either. I would not use silicone around the ports myself, I use copper spray, but still, was same before and after, no way it went back together the same bad way it was before it came apart.

Vacaum gauge shows a fluctuation. That and the hot egt on #6 are all we got.

This happened suddenly.

All that's left is the cam (flat exhaust lobe on #6?), possibly a collapsed lifter, or a yet undiscivered vacaum leak, close to the valve in the #6 intake port. Does this thing have pressed or screw in studs? Is a pressed stud pulling out, or a screw in stud loose? MAybe a real bad valve guide, tho it would seem weird to lose only one out of 16?

It has pressed in studs. All the rockers look like there going the same distance up and down. It never made a funny ticking sound. Would a collapsed lifter do that? I have always be Iffy about these heads. My brothers engine builder did them for me. When I go them they had the correct new springs, 3 angle valve job,reconditioned valves and 3 studs were higher than the others, I noticed white lube on all the valve stems and new guides. Its like he pressed the 3 studs in or something. I it also had 3 heli coils on the intake bolts. Put it this way I paid $400 for everything. I will check the studs but I don't think there loose.

mnm99
Apr 11th, 07, 06:37 PM
Agree with all said. But, with a pulled stud or unscrewed stud, rocker noise due to loose lash would be very noticeable. mnm99 didn't mention any noise other than a "soft/light" tic at idle.

I do agree it could be a worn cam lobe, unless mnm's been adjusting the valves and not noticing a loose valve/rocker arm.

I readjusted #6 and the stud seems tight and like I said It never made a noise all of a sudden. With a worn lobe would I notice a difference in rocker movement with the naked eye? I don't have a gauge right now to test it. I'm sure I could figure a way.

Guys thanks for all your help so far by the way!!

Youngladd
Apr 11th, 07, 07:05 PM
I have been following what was said and agree with everyone, everyone has their own way on diagnoising problems. My idea is pulling belt off water pump,removing thermostat start it up watch for air in coolant at intake. Cracked head? The head gasket doesn't settle with me because I would think it affect next door cylinders. I have to agree, For what was said before, I think you are going to find a cracked intake underside cyl #6. The trial of above is not going to show a cracked #6 intake runner on the head.GOOD LUCK! :(

zdld17
Apr 11th, 07, 07:27 PM
What 3 studs were higher than others? How much? Can you pull rocker arms off # 6 cly and look down inside to see if the bottom of the ball seat fulcrum is not pushed out or breaking away?

68SSConvt
Apr 11th, 07, 07:29 PM
mnm99 - I really don't have a suggestion as to your problem, but if a vacuum leak is a possible cause, I have a suggestion to confirm that you do or don't have a leak. I just posted about this test here http://www.camaros.net/forums/showthread.php?t=105570

Basically if you put the cylinder 1 at TDC on compression and loosen the intake rockers on any open intake valves (3, 4, and 6 I think or just loosen all intakes), and then block of the manifold at the carb (thin flat plastic bolted between carb and intake) then the intake should be totally sealed. If you then apply a vacuum or pressure to a fitting on the intake the intake should hold this vacuum or pressure once the pump is turned off. If it doesn't hold you should be able to hear where the leak is.

I used this test to confirm that my valve seals and intake gasket were good and that instead my heads were leaking oil into the intake past the rocker arm stud threads. (Teflon sealant didn't work.)

Hope this is some help,
Ray

77wolf10.85
Apr 11th, 07, 09:04 PM
Marc
Re what to look for on intake runner temps for a sticking valve. HOT HOT HOT.
And an apology of sortas... I said sticky or burned, meant to say sticky or not seating. Intakes don't burn usually, they get crap in the seat.

Your 3500 RPM temp check did show us something on 6. The engines I work on it would tell me I have a burned exhaust valve( and that shows up in a compression test that you have good) or a fuel system out of whack on an engine that has gas admission valves per cylinder. But an automotive engine not loaded, I'm not sure what it means. It means something though. Exhaust restriction on that tube?

I like Ray's Test. You could use an engine lifting plate with pipe threads tapped into it to seal and pressurize the intake. I'm gonna start doing that on the stand when I build em.
Now this next bit, I don't want anyone calling me names or taking any of this wrong. Last year while I was waiting on the correct length hardened pushrods for Wolf's 412 to come in from Comp, I wouldn't let myself run it any on the wrong ones other than the first bust off. And I had 10 days where I was home evry night and going crazy I was so mad at Comp... I built 2 engines, I built a run stand for Wolf's old engine out of an irrigation engine stand that had a tall deck 427 on it( gone dammit but that ended up giving an Iraq War Vet a damgood 355 but that's another story) and rigged it up, and I also did this truck and engine below and then sold it. Then I got Wolf's pushrods and quit doing silly stuff like this for a few months......
Insofar as silicone on intake gaskets, to each his own tastes and dislikes, but don't say it don't work. I was playing with a stock 305 last spring that a kid had put a cam into about 5 teeth off. It ruined one head pulled every stud out. He ruined the other by trying to screw a stud into a press-in hole. I inherited the whole damtruck on another kid deal(my kid this time)( he did a kid deal with the other kid). I just wanted to get rid of it and get back a little of my money. So I timed the cam and dug through my heads and came up with some I thought should run. Wrong. 1 day, 4 sets of heads and no new gaskets bought at all (read this no out of pocket expense) I had it running in my garage floor the way I wanted it to run with no smoke or misses. Yeah I run them on the floor, on a roll around square tubing engine stand, radiator and the whole works. Only takes 30-45 minutes to change heads on the floor. Took a lot longer to dig through heads and clean them up and leak test them. Guess I had em stacked up in there because they were junk. I ended up using a 350 head on one bank and one of the original 305 heads on the other, had to beat the rocker studs back in. It had 125 compression on the 350 side and 150 on the 305 side all even as heck(per bank). Sounded great. And all the lifters were scattered to hell and gone, so I found 16 with no wear on them and used them, they are still intact. And intake gaskets work just fine with silicone around all the ports. Sold the damtruck to a guy down the street. Still runs and sounds great. I hear it go past my house whenever I am home. The guy loves it. I put Wolf's old exhaust on it.

I would never dream of doing things like this to a "good" engine. But I work on machinery all day everyday and well into the night far too often in my younger days, and you learn what does and doesn't work in the middle of the night in the middle of nowhere. And I know head gaskets can be reused if you have to, and intake gaskets work just fine with silicone if you have to. And cam lobes could care less if a lifter is new as long as it doesn't have a wear pattern that alters the grind of the not-flat flat. And instead of buying a head gasket set I saved the bucks and put silicone on the intakes, and used it to pay for something I had bought for Wolf, probably some new Intake Gaskets the kind with Silicone already beaded into em :).

Totally unrelated, but thought some of you may enjoy.
This cam probably had 20 years on it. Continuous. Yes it's a roller. 1000 RPM engine. Sometimes you don't need a dial indicator, hehe.
That's if I succeeded in uploading it. My first attempt.

joe clance
Apr 11th, 07, 10:08 PM
Could it be a different rocker ratio on cylinder number six. either an intake or exhaust rocker mixed in by error ?

Joe Harrison
Apr 11th, 07, 10:32 PM
Intresting story wolf. Your right anything can work when you need it to or know how to make work.

I don't know if I would take off for along trip in that truck unless I had a bus ticket though. :D

mnm99
Apr 12th, 07, 05:28 AM
Recap.. My compression is between 158-162 on all. Does not blow smoke. Very smelly exhaust. Correct rockers.
My vac fitting is on the #8 intake runner that feeds the Power booster. I'm going to disconnect all fittings to the manifold and try it.

Heres the test results at 2500rpm for 30sec. This is what I found.

#2 = 320 #1 = 318
#4 = 375 #3 = 377
#6 = 650 #5 = 390
#8 = 399 #7 = 410

Something is up with this cylinder. What would cause this besides a bad intake gasket or vac leak? How about a bad valve? Wiped cam lobe?
I called the guy who built the heads and he says it sounds like a wiped lobe, So I call Comp Cams and they say it sounds like a valve! Gotta just laugh. I'm going to compare the lift from cylinder 4 and 6. It there the same that would rule out the cam right?
Remember I'm trying to find a rough idle miss.

JimM
Apr 12th, 07, 07:02 AM
I'd think this would show on the plugs.
Maybe put a brand new plug in #6 and in 1 other cylinder, run it at 2500-3500 for a few minutes, and compare them?

Difference between the plugs should show if #6 is lean.

mnm99
Apr 12th, 07, 09:53 AM
I'd think this would show on the plugs.
Maybe put a brand new plug in #6 and in 1 other cylinder, run it at 2500-3500 for a few minutes, and compare them?

Difference between the plugs should show if #6 is lean.

The plug does look cleaner than the others. I borrowed a dial gauge from a friend. I'm going to take readings tonight to see if my cam is good. Hopefully this will eliminate the cam. I'll post back.

Joe Harrison
Apr 12th, 07, 12:50 PM
Take you reading direct from the lifter if possible using a long feeler for the dial. Most come with several leanghts. Pre-load it some and set to zero and do a full revolution about 3 times and compair readings. Then do a good cylinder and see what you have. Remember to compare intake to intake exhaust to exhaust.

Speaking of heads:

What casting number or type of heads are running? What type of intake? Some later castings are more prone to cracks than others. 882 heads for instance can crack but still are not a bad cracking head. Now 624 heads crack all the time. They crack between valves or from seats, intake and exhaust runners and from spark plug holes. All other heads can crack here also but 624's are the worst. I have seen all of the above on 882's and basicly any mid 70's heads up to current versions of vortecs. If you have a head with 7 bolt hole exhaust manifold bolts you have a light casting head.

Joe

mnm99
Apr 12th, 07, 03:29 PM
I'm sorry I take that back. When I pulled the plugs just now to do the dial test they did look the same. I'll take a pic. I only dialed the 2 exhaust + 2 intake lobes on 4 and 6 so far and they are the same. What a pain! I'll go get the casting.

Here are the numbers I got.

Pass 8870128 or 8870123?

Drivers 8970126

I think they are 3970126 They are hard to read. If I had a bad lobe would I see it in the rocker movement? They all look the same at idle.

Sound right?

Joe Harrison
Apr 12th, 07, 04:39 PM
Need to dial it at the lifter. Hydraulic lifter is being pushed into the lifter by the spring tension and with the engine not runing it can be bleeding off as you rotate it. You want to do it similer to degreeing a cam. you would use a solid lifter for that but that's why I said to pre-load it and then zero your dial.

The casting number 3970126 comes back as 67-71 327/350 heads. if these heads do not have hard seats they could be having trouble. 71 or so is close to having factory induction hardened seats. Also old heads if they are hard seated can go to water around the seat when opening up for the new hard seat. They may not be cracked or crack when done but if thin can cause problems in a few miles or a few years it just depends how rusted they are from the water jacket out.

You might be left with only afew options if you can't find anything and that's to pull it apart. I would look at the cam first but then again heads are just as easy to pull when you get that far.

These heads could be cracked from the spark plug hole to the outside of the head. Each intake stroke it pulling air/vacume/leaking vacume to the cylinder. I have only ever seen one head cracked that bad in a spark plug hole. It was an angle plug 492 casting head. Pissed me off to!!! I had it welded and ran it anyway!!

Joe

Lonnie67
Apr 12th, 07, 04:46 PM
Also I am noticeing , I may be going crazy because of all the test I've done, but right around that cylinder I hear a clacking sound. Not a loose rocker sound or a rod knock, kinda K K K K , EVER SO SLIGHT.

Exhaust leak at header gasket? They sound just like valvetrain clacks. This might cause the hot header, not your miss though.

I quickly read both post and didn't see anyone mention this, but maybe I missed it.

mnm99
Apr 12th, 07, 04:51 PM
Need to dial it at the lifter. Hydraulic lifter is being pushed into the lifter by the spring tension and with the engine not runing it can be bleeding off as you rotate it. You want to do it similer to degreeing a cam. you would use a solid lifter for that but that's why I said to pre-load it and then zero your dial.

The casting number 3970126 comes back as 67-71 327/350 heads. if these heads do not have hard seats they could be having trouble. 71 or so is close to having factory induction hardened seats. Also old heads if they are hard seated can go to water around the seat when opening up for the new hard seat. They may not be cracked or crack when done but if thin can cause problems in a few miles or a few years it just depends how rusted they are from the water jacket out.

You might be left with only afew options if you can't find anything and that's to pull it apart. I would look at the cam first but then again heads are just as easy to pull when you get that far.

These heads could be cracked from the spark plug hole to the outside of the head. Each intake stroke it pulling air/vacume/leaking vacume to the cylinder. I have only ever seen one head cracked that bad in a spark plug hole. It was an angle plug 492 casting head. Pissed me off to!!! I had it welded and ran it anyway!!

Joe


Thanks. I did remove the rocker arm, brought the lobe to the lowest part and set my dial gauge right on top of the push rod and zeroed it out . Turned the engine by hand and saw the rod go up. I wasn't to sure how to read the gauge but it has a small dial thats 1-10 I would imagine 100th and the large dial thats 1000th. Both times it went to 3 on the small and 15 on the large. Anyway it was the same. I only did 6 and 4 though.

I did a compression check again for the heck of it while the plugs were out. This time the engine was warm and I got all 150's to 152's. I'm amazed how close they are.

Question.... What is accomplished by doing a compression check. What does it EXACTLY tell you. I hear leak downs are better, but what solid facts come from a compression? When I talked to comp cams they said if my compression is good the cam is good. How correct is that?

I want to bring it somewhere to verify my ignition is good before I start pulling heads. I know I verified this 2x but for a piece of mind I would like someone else that does this for a living to tell me.
Thanks.

zdld17
Apr 12th, 07, 05:05 PM
Roughly, sounds like you got .315 lift before rocker arm , then x 1.5 = .470 valve lift? How big did you say your cam was?

Joe Harrison
Apr 12th, 07, 05:19 PM
A compression test will tell you if your even accross your cylinders. You want a variance of less than 10%.

If it's low and you squirt oil in the cylinder and the compression goes up you have a cylinder seating problem that is most likey rings or wear. If nothing happens it's a head gasket or stuck valve basicly something above the short block..........or a hole in the piston or some other major short block damage.

leak down tests make it easy to pin point the problem with the leaking air. both are good and complement each other. With both valves closed and not operating you may or may not get compression. You have to get air into the cylinder to get compression. if loosen the rocker complety off the valve so it's not touching the spring at all on both intake and exaust (heck remove them) bring the piston to TDC install the compression tester and turn it over you should have very little compression. If it gets the 150-160 or your normal reading, air is coming into the cylinder from someplace. Your valves may not be sealing to the seat, gasket bad around cylinder or cracks in head or block?

Some one correct me if I am wrong. but if you close it all off the reading should not be much, you can only compress the amount of air in the cylinder. With it at TDC that is not much. When the piston strokes and the reading goes to normal it would have to be getting air from some place other than the normal intake route correct??

Joe

mnm99
Apr 12th, 07, 05:25 PM
Roughly, sounds like you got .315 lift before rocker arm , then x 1.5 = .470 valve lift? How big did you say your cam was?

280H comp cam. I would give or take a little since it's my first time.
Part Number 12-212-2
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS 280H-10
Description

--------------------------------------------------------------------------------

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.48 0.48
Duration At 0.006 Tappet Lift 280 280

--------------------------------------------------------------------------------

Valve Timing At 0.006
Open Close
Intake 34 66
Exhaust 74 26

--------------------------------------------------------------------------------

These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 230 230
Lobe Lift 0.32 0.32
Lobe Separation 110

--------------------------------------------------------------------------------

Joe Harrison
Apr 12th, 07, 05:27 PM
Hell I just thought of something. You might have a crack at the heated exhaust crossover to the #6 intake port. That port is under pressure with hot exhaust gases. It could also be in your intake if it's cast iron. If you pressureize the cylinder with the exuahst open in #6 and close up all the others intakes by loosening the rocker arms so the valves come all the way up. make sure your #6 intake valve is closed and the piston in #6 at BDC. put that 100 PSI on it and listen at the carb. If you hear something coming through the carb it can only be the intake valve not seating or a crack.

Joe

zdld17
Apr 12th, 07, 05:32 PM
280H comp cam. I would give or take a little since it's my first time.
Part Number 12-212-2
Engine 1955-1998 Chevrolet
262ci-400ci
8cyl.
Grind Number CS 280H-10
Description

--------------------------------------------------------------------------------

Intake Exhaust
Valve Adjustment 0 0
Gross Valve Lift 0.48 0.48
Duration At 0.006 Tappet Lift 280 280

--------------------------------------------------------------------------------

Valve Timing At 0.006
Open Close
Intake 34 66
Exhaust 74 26

--------------------------------------------------------------------------------

These Specs Are For The Cam Installed At 106 Intake CL
Intake Exhaust
Duration At 0.05 230 230
Lobe Lift 0.32 0.32
Lobe Separation 110

--------------------------------------------------------------------------------

Your cam advertised at .480, you measure about .470. Done deal, move on to something else , Wouldn't you guys say so? Sounds like Joe thought if something else.

Joe Harrison
Apr 12th, 07, 05:43 PM
I would say so Don. I don't think it can get any closer than that.

Dang only problem with what I posted above is. You need to plug the exhaust at the header/manifold. Or close off all exhaust valves on that bank 2,4,and 8 by loosening rockers to them also. Still have the problem of air going out exhaust though....Dang it.

Any ideas guys??

Joe

77wolf10.85
Apr 12th, 07, 08:19 PM
Pull the heads and be done with it.

But I think I would put the left bank head on the right bank and vice versa if I didn't see a problem. And see if the problem switches banks. Whether or not you buy new gaskets is up to you.:noway:
You can leak test your intake valves with water and the head on it's side, older heads will trickle a teeny bit from intakes because they get crap in the seats.
You can do the same to the exhaust but the crossover port loses all your water on the center exhausts. Stuff a rag in it and you'll get a quick test.

TMessick
Apr 13th, 07, 12:24 AM
I'm coming from EFI and distributorless ignition land, but if you had an odd retarded spark on one cyl it would also raise EGT significantly. Not sure how this would happen with a distributor (problem with the cap?) But it might be worth clocking the distributor and moving your plug wires just to verify. Kind of a long shot, but thought I'd throw it out there...

mnm99
Apr 13th, 07, 03:54 AM
I'm coming from EFI and distributorless ignition land, but if you had an odd retarded spark on one cyl it would also raise EGT significantly. Not sure how this would happen with a distributor (problem with the cap?) But it might be worth clocking the distributor and moving your plug wires just to verify. Kind of a long shot, but thought I'd throw it out there...

Thanks. I tried that too.:(

mnm99
Apr 13th, 07, 03:57 AM
Pull the heads and be done with it.

But I think I would put the left bank head on the right bank and vice versa if I didn't see a problem. And see if the problem switches banks. Whether or not you buy new gaskets is up to you.:noway:
You can leak test your intake valves with water and the head on it's side, older heads will trickle a teeny bit from intakes because they get crap in the seats.
You can do the same to the exhaust but the crossover port loses all your water on the center exhausts. Stuff a rag in it and you'll get a quick test.

Like I said, once I verify the ignition and do a leak down I think I'm pulling the heads. It would make me feel better kinda knowing whats wrong before I do that.

Everett#2390
Apr 13th, 07, 05:03 AM
Marc has done the air supply test to the cylinder and reported he did not hear any leakage at the tailpipe(s) and no bubbles in the coolant. But, he did say he heard an air leak. I would have placed a balloons over the tailpipe, or small condoms..........LOL

Marc has ruled out camshaft, valvetrain, short block, and most other maladies. gaskets are the only items left.

Joe Harrison
Apr 13th, 07, 03:36 PM
The one place that can not rule out is the exhuast cross over in the head. It could be cracked and leaking to the intake runner side of #6. The exhaust cross over shares a casting wall with the #6 intake port, also #4. On the right bank #3 and #5.

Joe

mnm99
Apr 13th, 07, 04:52 PM
The one place that can not rule out is the exhuast cross over in the head. It could be cracked and leaking to the intake runner side of #6. The exhaust cross over shares a casting wall with the #6 intake port, also #4. On the right bank #3 and #5.

Joe

I hear ya. My intake doesn't have the crossover and the gasket blocket the heads off. I can see if it's cracked on the head. We'll see. I've been looking at the Brodix IK200 and the Sportsman II heads.

What piece of test equiptment could tell 100% that the ignition is good? Could the ignition even do that to temps?

Joe Harrison
Apr 13th, 07, 09:30 PM
Scope on the ignition. The old school test!! So to test you cross over all you need to do is disconnect your header/exhaust manifold. Block the exhaust port Put the piston at BDC. and remove the rockers from the intake and exhaust on #6. Run pressure in from the spark plug hole. If your getting pressure or air coming out the carb it has to be one of two things. Intake valve not sealing because it's burnt, cracked, bad seat stuck in a guide and not closing all the way or there is a crack going to the intake side via exhaust cross over etc. Basily will narrow it down to a head problem of some sort.

Joe

jaguareats
Apr 13th, 07, 10:13 PM
:beers: mnm lol cheers told you sell me car thought you had a weird problem with car.when i talked to you. it is getting weirder by the minute.for a tach install hhhhmmm.

mnm99
Apr 14th, 07, 04:45 AM
Scope on the ignition. The old school test!! So to test you cross over all you need to do is disconnect your header/exhaust manifold. Block the exhaust port Put the piston at BDC. and remove the rockers from the intake and exhaust on #6. Run pressure in from the spark plug hole. If your getting pressure or air coming out the carb it has to be one of two things. Intake valve not sealing because it's burnt, cracked, bad seat stuck in a guide and not closing all the way or there is a crack going to the intake side via exhaust cross over etc. Basily will narrow it down to a head problem of some sort.


Joe

I tried that except blocking off the exhaust. I listened in the exhaust tube for air and didn't hear any. I did it on 2,4,6 and they all sounded the same. The only air I heard/felt was the dipstick tube, I don't have a gauge so I don't know how much is normal. They all sounded the same though. I want to find someone with a scope.

mnm99
Apr 14th, 07, 04:47 AM
Scope on the ignition. The old school test!! So to test you cross over all you need to do is disconnect your header/exhaust manifold. Block the exhaust port Put the piston at BDC. and remove the rockers from the intake and exhaust on #6. Run pressure in from the spark plug hole. If your getting pressure or air coming out the carb it has to be one of two things. Intake valve not sealing because it's burnt, cracked, bad seat stuck in a guide and not closing all the way or there is a crack going to the intake side via exhaust cross over etc. Basily will narrow it down to a head problem of some sort.


Joe

I tried that except blocking off the exhaust. I listened in the exhaust tube for air and didn't hear any. I did it on 2,4,6 and they all sounded the same. The only air I heard/felt was the dipstick tube, I don't have a gauge so I don't know how much is normal. They all sounded the same though. I want to find someone with a scope. Could an ignition problem make temps like that? I put my timing light on #6 since it fires the same as #1 and the timing was on.:clonk:

mnm99
Apr 14th, 07, 09:22 AM
My engines getting pissed at me! I don't think it wants me to touch it anymore.. I went to start it this morning and hear a loud bang the a grinding sound.. Turns out my starter split in 2:hurray: ...LOL. Went to Autozone and got my free replacement... I'll show her. I'll bolt it up tonight! :sad:

mnm99
Apr 14th, 07, 11:03 AM
My engines getting pissed at me! I don't think it wants me to touch it anymore.. I went to start it this morning and hear a loud bang the a grinding sound.. Turns out my starter split in 2:hurray: ...LOL. Went to Autozone and got my free replacement... I'll show her. I'll bolt it up tonight! :sad:


Gets better.....For the heck of it I wanted to check out the pickup on the dist. So i removed the dist and took it apart finding the magnet on the pickup was broke in half . Who knows... I had a new one and wanted to install it for the heck of it anyway. When I ohmed out the old one it came out good per MSD. SO...I installed the new one and put the dist in the car finding out the I put the magnet in backwards.:wacko: So I took it out and fixed that. Haven't gotten to start it yet.

wrote this on MSD's site.

I've been trying to find a problem for a while now. I decided to take out the dist and check out the pickup. I ohmed it out and it said fine. I had an extra one so I decided to replace it. NOW, upon removel either I may have cracked the magnet or it was cracked already. I removed the 2 nuts and slid it out easy and the magnet came apart in 2, cracked down the middle. I didn't force it or anything so I can't see how I broke it, but who knows. What symptons would it have to my engine. I am haveing a problem that I've been trying to track down. I want to see if you say what could happen before I tell you whats happening.

Response

I've been thru that once a long time ago---forgot most about what happened but as I recall the timing was erratic and the rotor index was affected----to where the rotor tip spark had bad scatter jumping across to the cap terminals.
-------------------------------------
-AND--the replacement magnet can be installed two ways---right side up or upside down----which changes the north/south polarity-----and this affect the rotor index and timing in relation to the reluctor paddles.

-I THINK this magnet orientation might also need to be reversed depending on the rotation of the distributor---but I'm not positive about this---never actually went thru the actual testing of that yet.

Who knows


I need a vacation!

JimM
Apr 14th, 07, 11:23 AM
but as I recall the timing was erratic and the rotor index was affected----to where the rotor tip spark had bad scatter jumping across to the cap terminals.
-------------------------------------
-AND--the replacement magnet can be installed two ways---right side up or upside down----which changes the north/south polarity-----and this affect the rotor index and timing in relation to the reluctor paddles.

AND you didn't start it yet?

methinks this could be it...

when you put the ole points distributor back in, assuming you didn't rig a ballast resister, you'd get a lot of points arcing and spark scatter too.

Joe Harrison
Apr 14th, 07, 11:36 AM
If it's having a spark scatter problem it could be having a pre ignition problem, basicly detonation. This will cause the cylinder to run hot as it's basicly lean. The rattle or knocking, ticking noise you hear might be the detonation sound.

I don't think you have any issues at the head from reading your post if you did not hear anything coming out the exhaust but what the intake? ohh wait need to pressurize the exhaust cross over which means having the exhaust valve open and blocking the exhaust port to the header/manifold. That will eliminate the cross over. Or pressureize the exhaust port with the valve closed might the easy way to do it.
The cross over does not get exhaust pressure until the exhaust valve opens. In your case the intake blocks it from going to the other bank.

mnm99
Apr 14th, 07, 11:53 AM
AND you didn't start it yet?

methinks this could be it...

when you put the ole points distributor back in, assuming you didn't rig a ballast resister, you'd get a lot of points arcing and spark scatter too.

I'm not getting my hopes up.

No I didn't start it yet. I'm working today, kinda.LOL. I went home for a brake and thats when my starter broke. I i took it out and went back to work. I got a new one on my way back. I ended up going home on my lunch brake and fixing the backwards magnet that I put in the dist. I didn't have time to put the starter in yet. My parents are comming over for dinner so it looks like I won't be able to start it until tommorrow!:(

I hooked up the resistance wire that was factory, but I never tested the voltage. It worked before so...

You guys will be the first to know!

zdld17
Apr 14th, 07, 12:51 PM
If there were a 100 people waiting in line to get change for a dollar and you were the last one, you would have to be the one to get took. Your luck.

Your finding makes a lot of sense, a broken magnet pickup, that means to me that if the magnet spread, then the pull on the reluctor or hall blade would also be spreading? , thus trying to change ign timing. I have never heard of this happening, Also , if one magnet that has a north and south pole, then a broken one would have two of each and the end of each is opposing each other??? Got any engineers out there?

As for the magnet going in two differant ways, I have never heard this but I have now. Sounds like your problem is about solved.

mnm99
Apr 14th, 07, 01:05 PM
If there were a 100 people waiting in line to get change for a dollar and you were the last one, you would have to be the one to get took. Your luck.

Your finding makes a lot of sense, a broken magnet pickup, that means to me that if the magnet spread, then the pull on the reluctor or hall blade would also be spreading? , thus trying to change ign timing. I have never heard of this happening, Also , if one magnet that has a north and south pole, then a broken one would have two of each and the end of each is opposing each other??? Got any engineers out there?

As for the magnet going in two differant ways, I have never heard this but I have now. Sounds like your problem is about solved.

Thanks, now stop getting my hopes up. I can't work on this until tommorrow! LOL

68rs406
Apr 14th, 07, 01:22 PM
That would do it, question is why is it broken, and why did it start acting like this for no apparent reason, you were not working on the distributor right?
Hmm, crazier things have happened and that would definately make it do what it was doing, if it fixes it then cool but man I hate those problems that get fixed without explanation, you never know when they may pop up again.
Good luck, and I'd be calling in sick today.....:D

zdld17
Apr 14th, 07, 01:25 PM
That would do it, question is why is it broken, and why did it start acting like this for no apparent reason, you were not working on the distributor right?
Hmm, crazier things have happened and that would definately make it do what it was doing, if it fixes it then cool but man I hate those problems that get fixed without explanation, you never know when they may pop up again.
Good luck, and I'd be calling in sick today.....:D


I believe those magnets are fastened down with two screws into the dist body, i can see how you could overtighten and break on in half.

68rs406
Apr 14th, 07, 01:43 PM
Oh definately, I agree. But he was doing something completely unrelated, like installing a tach or something (?) when it started acting up. Thats what makes me wonder :confused: .
Unless it was overtight to begin with and heat cycling or something made it crack at an unkown time, it just seems odd it would all of a sudden crack.
Hope it is the problem though :cool:

mnm99
Apr 14th, 07, 02:02 PM
That would do it, question is why is it broken, and why did it start acting like this for no apparent reason, you were not working on the distributor right?
Hmm, crazier things have happened and that would definately make it do what it was doing, if it fixes it then cool but man I hate those problems that get fixed without explanation, you never know when they may pop up again.
Good luck, and I'd be calling in sick today.....:D

I havent worked on the dist before today. This is the first time I took a look inside. MSD told me to do a OHM test 3 weeks ago and said if it's between 400-1400 ohms there nothing wrong with the dist. This wouldn't test a broken magnet though. Exactly , why would it break? I bet it's not the problem anyway.

JimM
Apr 14th, 07, 03:50 PM
oh just go home and start the damned thing all ready, I can't stand the suspence!

mnm99
Apr 14th, 07, 05:08 PM
Well I could'nt wait... GOOD NEWS.......The starter works! Bad news is I have the same problem! DAMN!:mad: :mad: :mad: :mad:

Joe Harrison
Apr 14th, 07, 07:06 PM
Man I am out of thoughts but one last place is to put pressure on that exhaust port to the manifold with the exhaust valve closed and see if you get air coming into the intake. You going to need about 100 PSI or more. If you close off the intake valve the only place for it to go is the intake and you should hear or feel air coming from there.

This will eliminate the head as a culprit.
Joe

77wolf10.85
Apr 15th, 07, 08:16 AM
I am sympathetic with wanting to know what the problem is before you pull heads, and wanting to "scope the ignition" BUT... when you don't have tools you have to use the tools available to you to achieve the same end

To eliminate or verify the head as the culprit

put the left bank head on the right bank and vice versa

If 6 stays bad, it ain't the head. If the problem goes to the other side you have 1 bad head. If the problem goes away..

mnm99
Apr 15th, 07, 08:33 AM
I am sympathetic with wanting to know what the problem is before you pull heads, and wanting to "scope the ignition" BUT... when you don't have tools you have to use the tools available to you to achieve the same end

To eliminate or verify the head as the culprit

put the left bank head on the right bank and vice versa

If 6 stays bad, it ain't the head. If the problem goes to the other side you have 1 bad head. If the problem goes away..

If I'm gonna do that I'm going to get new heads. I have 1.94 stock irons now. I was looking at the Brodix IK200 but the valve spring won't work with my cam. On the other hand the IK180's will. Or the Sportsman II will work too, but for an extra $100 I could go aluminum.

68SSConvt
Apr 15th, 07, 08:51 AM
Several days ago I suggested a test you could do to positively identify a vacuum leak. I haven't read any posts since that says you have tried this or have in any other way ruled out a vacuum leak.

Have you ruled out a vacuum leak? If not, why don't you try this test? This would tell you positively that you do or don't have a vacuum leak and also help you find it. I'd try this before pulling the heads. (Personally I would hate to pull the heads and never be able to find out this was a simple intake gasket leak or something. Not that I'm saying the problem is a vacuum leak, just that this could rule that out.)

Ray

Joe Harrison
Apr 15th, 07, 09:00 AM
If your pulling the heads I would have them thoughly Checked, cleaned maged my a shop. Don't go to the guy that built them. If they are bad or one is cracked or other problems found on the the #6 head (use a metal stamp to mark the head) then you may be able to work something out with the shop that did them.

For $100 aluminum is a good way to go. You can raise the compression by getting a smaller chamber and get more H/P. Aluminum heads keep temps down in the chamber.
Other options are vortecs but you will need a new intake....bummer. Vortecs are cheap and provide excellent performance and if anything does happen to one they are just a Chevy dealer away no matter where your at.

Joe

Joe Harrison
Apr 15th, 07, 09:01 AM
Several days ago I suggested a test you could do to positively identify a vacuum leak. I haven't read any posts since that says you have tried this or have in any other way ruled out a vacuum leak.

Have you ruled out a vacuum leak? If not, why don't you try this test? This would tell you positively that you do or don't have a vacuum leak and also help you find it. I'd try this before pulling the heads. (Personally I would hate to pull the heads and never be able to find out this was a simple intake gasket leak or something. Not that I'm saying the problem is a vacuum leak, just that this could rule that out.)

Ray

I think Harbor Frieght sells a Air Compressor operated vacuum pump for about $30.00?

Joe

mnm99
Apr 15th, 07, 09:20 AM
Several days ago I suggested a test you could do to positively identify a vacuum leak. I haven't read any posts since that says you have tried this or have in any other way ruled out a vacuum leak.

Have you ruled out a vacuum leak? If not, why don't you try this test? This would tell you positively that you do or don't have a vacuum leak and also help you find it. I'd try this before pulling the heads. (Personally I would hate to pull the heads and never be able to find out this was a simple intake gasket leak or something. Not that I'm saying the problem is a vacuum leak, just that this could rule that out.)

Ray
I have a vac pump that I was going to use for my power brakes. It shut off at 22in of vac. If I made a plate is this too much vac? I'll get the parts together and let you know.

Everett#2390
Apr 15th, 07, 09:57 AM
I have a vac pump that I was going to use for my power brakes. It shut off at 22in of vac. If I made a plate is this too much vac? I'll get the parts together and let you know.No, the more vacuum, the better.

If making a plate to fit/test, you can use a MityVac hand pump and watch the gauge. Or inject shop air and listen/spray soapy water for leaks.

mnm99
Apr 15th, 07, 02:11 PM
I made a plate and hooked up the vac pump. loosened the rockers that were down. The pump held for around 20 seconds before it went back on. It kicks back on at 15in and off at 22. I listened for leaks and sprayed water. I didn't find anything. It had to be going somewhere because the pump works fine. I just couldn't find it! When I pushed a valve down I heard the air real clear. If there was a valve not seating the soap and water wouldn't work and I didn't want to spray it in the rocker area. blowing air I couldn't hear either

77wolf10.85
Apr 15th, 07, 02:47 PM
guides
maybe try squirting oil around the valve stems

kustomwerker
Apr 15th, 07, 04:29 PM
a crack in the seat, or dislodged seat will give you a leak...could be a high pressure crack that only opens when it gets warm...i recently had 1 on a ford 302 from jasper that ran fine but consumed coolant...the seat pulled out of the head just enough that when warm, it pushed coolant...couldnt test under pressure, and believe me, i tried...also tried pressurizing the coolant jacket, with no luck...sometimes ya just have to bite the bullet and rip it down...

72Tugboat
Apr 15th, 07, 08:58 PM
How would you get detonation at idle? And why would spark scatter affect only one cylinder consistently?

Good Luck!

joe clance
Apr 15th, 07, 09:13 PM
switch the rocker arms sets on #6 and #1 and re-measure header tube temps. Its too easy to do! And too hard to see any ratio differences that may be inherent or by error.

joe c

joe clance
Apr 15th, 07, 09:40 PM
If the rocker set swap does not reveal the temp changes to the other cylinder, i would look at the exhaust lifter on #6.
EXh #6 is probably not pumping up and causing un-due pressure (and excellerated temperatures) in cylinder #6 after repeated cycles. It may be bleeding off with use/time, and not detectable with comp and leak tests.



Since cylinder #4 is not adversely affected by #6's temps and misfires, you're wasting your time looking for leaks between #4 and #6.

joe c

Joe Harrison
Apr 15th, 07, 10:18 PM
How would you get detonation at idle? And why would spark scatter affect only one cylinder consistently?

Good Luck!

Carbon track/path in the cap due to cracks or age, being dropped dirt and he has a broken magnet which if it putting off material will attract spark. Detonation is just preignition of fuel/air charge as it's being compressed to fire. You may or may not hear it but it will bring temps up and heat up a cylinder. After it get carbon glowing or burnt or spot on the piston you have a little glow plug to do it for you.

joe clance
Apr 15th, 07, 10:43 PM
[Carbon track/path in the cap due to cracks or age, being dropped dirt and he has a broken magnet which if it putting off material will attract spark. ]

True and quite possible, however would not this manifest a misfire between cylinders? would more than one cylinder be affected?
Seems that misfires and excellerated temperaturs would be apparant in the carbon tract to the other cylinder also.

joe c

Everett#2390
Apr 16th, 07, 05:26 AM
mnm, you're supposed to pressurize the volume after you've seen a vacuum leak. However, how leak free is the pump you are using?

Pressurize the volume and spray with soapy water. You'll see bubbles as the air pressure blows out. A vacuum sucks in.

I believe we could eliminate the ignition system as he has swapped it out already.

mnm99
Apr 16th, 07, 05:36 AM
mnm, you're supposed to pressurize the volume after you've seen a vacuum leak. However, how leak free is the pump you are using?

Pressurize the volume and spray with soapy water. You'll see bubbles as the air pressure blows out. A vacuum sucks in.

I believe we could eliminate the ignition system as he has swapped it out already.


If I put my finger over the pump it will hold for for as long as I hold it. I tried pressurizing it. Couldn't find anything.

mnm99
Apr 16th, 07, 05:41 AM
If the rocker set swap does not reveal the temp changes to the other cylinder, i would look at the exhaust lifter on #6.
EXh #6 is probably not pumping up and causing un-due pressure (and excellerated temperatures) in cylinder #6 after repeated cycles. It may be bleeding off with use/time, and not detectable with comp and leak tests.



Since cylinder #4 is not adversely affected by #6's temps and misfires, you're wasting your time looking for leaks between #4 and #6.

joe c

Wouldn't I see the rocker not moving up and down as far ,if the lifter was the problem? They all look the same. I don't think the rocker is the problem.

Everett#2390
Apr 16th, 07, 05:46 AM
If I put my finger over the pump it will hold for for as long as I hold it. I tried pressurizing it. Couldn't find anything.Sorry, I didn't read you had already pressurized it.

You've done the rocker arm trick before and you found nothing unusual there. You measured its travel and compared with another.

It would be nice to find a smoke attachment to apply to shop air supply. This way, you could "see" the smoke rise from the crack.

Time for another cup of java this AM.

mnm99
Apr 16th, 07, 06:43 AM
I think this process aged me a few years..... I'm only 36! This shouldn't happen.

I have an apointment with a friends mechanic next monday. When i brought it to him a couple of weeks ago he said it was the ignition. Don't get me wrong he's a very nice guy and does know his stuff from everyone I talk to. I was only ther for 10 min when he told me that. He wants me to drop it off so he can dig into it more. Just after all I have done I don't feel very confident. This is what he does for a living so who knows.

This may be a crude way of doing this but I'm going to give it a try. I have a 1 foot small ruler and 2 valve covers that are cut open. With the car running I should be able to see the marks on the ruler at the highest and lowest point if I rest it on the head and measure it. If they are the same This would rule out a lifter or a lobe.

If a lobe IS bad how much of a difference would I notice? 1/16" , 1/8" ect?
I don't think it's it but this would I hope rule this out once and for all!

joe clance
Apr 16th, 07, 07:07 AM
Wouldn't I see the rocker not moving up and down as far ,if the lifter was the problem? They all look the same. I don't think the rocker is the problem.
You will not visually detect any difference ! As far as the lifter, it may be fine statically and return to its pre set adjustment after use. during use, however, it will fail to pump up and not allow the cylinder to expell all of the gasses, raising temps and requiring a greater energy to ingite the resulting higher than normal compression in that cylinder.

this has to be someting simple!

joe c

Everett#2390
Apr 16th, 07, 07:09 AM
If a lobe IS bad how much of a difference would I notice? 1/16" , 1/8" ect? I don't think it's it but this would I hope rule this out once and for all!You've done this feat already. The distance seen would be dependent upon the amount of lobe wear. Obviously, the more the wear, the less the distance traveled by the rocker arm.

Any great wear will be accompanied by rocker arm clatter as the lash has increased.

mnm99
Apr 16th, 07, 10:34 AM
You will not visually detect any difference ! As far as the lifter, it may be fine statically and return to its pre set adjustment after use. during use, however, it will fail to pump up and not allow the cylinder to expell all of the gasses, raising temps and requiring a greater energy to ingite the resulting higher than normal compression in that cylinder.

this has to be someting simple!

joe c

Would I notice this on a compression test? Because they were all the same.

joe clance
Apr 16th, 07, 11:18 AM
nope

72Tugboat
Apr 17th, 07, 04:55 AM
If a lifter was bleeding down, wouldn't it show up in the measurements he's done without the engine running (no oil pressure)?

Good Luck!

mnm99
Apr 17th, 07, 05:39 AM
[QUOTE=72Tugboat;766049]If a lifter was bleeding down, wouldn't it show up in the measurements he's done without the engine running (no oil pressure)?

Good Luck![/QUOTE

I really don't think it's a lifter? BUT IF IT WAS...How would it be tested? My oil pressure is 65-70psi cold and 35 warm at idle.

72Tugboat
Apr 17th, 07, 06:45 AM
I don't think it's a lifter either, or you wouldn't measure within .010 of the spec'd lift. If it was bleeding down enough to cause the problem when running I'd think it would make a lot of noise.

The compression test indicates the intake closing points are consistent under those conditions (cranking).

You said the vacuum held when you put your finger over the pump, right? Did this test do both sides of the manifold or just one? What manifold is it?

Good Luck!

mnm99
Apr 17th, 07, 07:53 AM
I don't think it's a lifter either, or you wouldn't measure within .010 of the spec'd lift. If it was bleeding down enough to cause the problem when running I'd think it would make a lot of noise.

The compression test indicates the intake closing points are consistent under those conditions (cranking).

You said the vacuum held when you put your finger over the pump, right? Did this test do both sides of the manifold or just one? What manifold is it?

Good Luck!


Both sides. I flipped the plate around. I will double check the pump to see how long it holds. Edlebrock RPM

What do you guys think about replacing the intake gaskets AGAIN? Remember when I did this the first time it came out the same. This time I'll only put silicone around the water jackets and ends.

Everett#2390
Apr 17th, 07, 09:29 AM
Certainly wouldn't hurt. I'd would susbstitute a 1/4 inch diamemter bead of RTV for the end seals instead of using the supplied end seals.

Clean all gasket surfaces with either BraKleen or lacquer thinner to remove any trace of oil.

mnm99
Apr 17th, 07, 10:36 AM
Certainly wouldn't hurt. I'd would susbstitute a 1/4 inch diamemter bead of RTV for the end seals instead of using the supplied end seals.

Clean all gasket surfaces with either BraKleen or lacquer thinner to remove any trace of oil.


I did all that the 1st and 2nd time. I cleaned it 3x with acitone. I think I'm going to hold off untill the leak down test.

Here's a suggestion I got from someone else, what do you think? I was told it can tell a rich condition ot lean. At an Idle take a temp reading at the header. Keep taking the reading and tap the accelerator pump on the carb. This will allow more fuel in without adding more air. If the temp goes up on that tube it will be a rich condition (good). If the temp goes down it's a lean condition (bad). I would compare a couple of tubes. If #6 goes down and say #4 goes up. Theres a vac leak on that cylinder.

I've never heard of this , but at this point I'll try anything!

Everett#2390
Apr 17th, 07, 12:06 PM
I did all that the 1st and 2nd time. I cleaned it 3x with acitone. I think I'm going to hold off untill the leak down test.I can see where you would be alittle hestitate in doing a 3rd time.Here's a suggestion I got from someone else, what do you think? I was told it can tell a rich condition ot lean. At an Idle take a temp reading at the header. Keep taking the reading and tap the accelerator pump on the carb. This will allow more fuel in without adding more air. If the temp goes up on that tube it will be a rich condition (good). If the temp goes down it's a lean condition (bad). I would compare a couple of tubes. If #6 goes down and say #4 goes up. Theres a vac leak on that cylinder.

I've never heard of this , but at this point I'll try anything!Not a bad idea, makes sense. If the engine is not apart yet, try it. What is there to lose, except for time?

mnm99
Apr 17th, 07, 12:10 PM
I can see where you would be alittle hestitate in doing a 3rd time.Not a bad idea, makes sense. If the engine is not apart yet, try it. What is there to lose, except for time?

No not apart yet. I'll wait for the leak down first. I'll give it a try when I get home.

Hey. Did you see my other post if I was to get new heads?
http://www.camaros.net/forums/showthread.php?t=105300
Take a look at the piston. What do you think?

mnm99
Apr 17th, 07, 02:45 PM
I did all that the 1st and 2nd time. I cleaned it 3x with acitone. I think I'm going to hold off untill the leak down test.

Here's a suggestion I got from someone else, what do you think? I was told it can tell a rich condition ot lean. At an Idle take a temp reading at the header. Keep taking the reading and tap the accelerator pump on the carb. This will allow more fuel in without adding more air. If the temp goes up on that tube it will be a rich condition (good). If the temp goes down it's a lean condition (bad). I would compare a couple of tubes. If #6 goes down and say #4 goes up. Theres a vac leak on that cylinder.

I've never heard of this , but at this point I'll try anything!

So much for that test....... at 1000rpm for 1 min I bliped the accelerator pump and the temps came down ( lean cond). But this happend on 3 other tubes also! The temp on #6 was still 175* hotter that the others.

mnm99
Apr 19th, 07, 04:59 PM
LEAKDOWN RESULTS

Well this is good and bad. Here are the results using a Snap-on duel gauge.

Cylinder #1 = 4% or 96
Cylinder #2 = 2% or 98
Cylinder #3 = 5% or 95
Cylinder #4 = 3% or 97
Cylinder #5 = 4% or 96
Cylinder #6 = 5% or 95
Cylinder #7 = 2% or 98
Cylinder #8 = 4% or 96

I'm happy there good but I still can't find the miss. I could try swapping the springs from 4 to 6, but I never did that and don't have the tool. Maybe pull the manifold again?:sad:

What do you think?

Mkelcy
Apr 19th, 07, 05:14 PM
Maybe pull the manifold again?:sad:

What do you think?

Have you swapped manifolds yet?

mnm99
Apr 19th, 07, 06:09 PM
Have you swapped manifolds yet?

What do you mean swap manifolds? I already changed gaskets.

travis
Apr 19th, 07, 06:20 PM
Could be an internal leak in the manifold itself, like a porous casting with a pin hole in a runner. Its definately cheaper and easier than swapping heads. Even a cleaned up stocker will work for this test.

What kind of intake do you have, anyway?

zdld17
Apr 19th, 07, 06:24 PM
Could be an internal leak in the manifold itself, like a porous casting with a pin hole in a runner. Its definately cheaper and easier than swapping heads. Even a cleaned up stocker will work for this test.

What kind of intake do you have, anyway?
If you have the option, get one with out egr and crossover stuff.

mnm99
Apr 19th, 07, 06:27 PM
I have a appointment with a mechanic on monday. We'll see what happens. If he can't find anything I'll end up pulling the intake AGAIN.

Performer RPM intake

mnm99
Apr 23rd, 07, 11:55 AM
Well the mechanic called and said it's my springs..??? When they tested them he said he got 45lbs of pressure on the springs at seat before the valve started to open. Somethings weird. Either he did the test wrong or there is a problem with all the springs. I called the engine guy who built the heads and he told me theres nothing wrong with the springs. He said if the seat pressure was 45lbs I would be getting all kinds of popping and stuff at higher rpms. He also said if the compression is good and the leak down is good there's nothing wrong with the heads. I don't know....I told the mechanic If he thinks that is the problem then replace them. If this isn't the problem and he does the work am I responsible for the work?

kustomwerker
Apr 23rd, 07, 04:12 PM
if you authorize the work, you`re on the hook for the bill...seat pressures like that seem very light!!!i would think with those pressures, you would float valves very easily...i would think 145 would be a more correct number...i know on our bigblock, the seat pressure is up around 265, but much larger valves...i think on a small block with 2.02 i would expect to see 175 on up at the seat...but i could be wrong...did they leave the inner spring out when breaking in the cam???i`ve done this to prevent cam failures...

dawg
Apr 23rd, 07, 04:44 PM
im sure those are cam break in springs.
local engine shop said so.
with the low pressure around 45 to 75 .
lower seat pressure springs used since they started taking out the zinc in the breakin oil.
so you wont wipe out a new cam.
im betting new springs and the car will wake up.
I just tested my springs and i got a reading of 210 +_ 5.
Ive check enough spring pressures to know how to do it.
At least youll have good springs and other problem might go away.

mnm99
Apr 23rd, 07, 05:26 PM
He showed me the spring pressure using a gauge that grabs the front part of the rocker where the pushrod is and by pulling the lever down shows a arm pointing at the pound amount. All the springs showed 45 lbs on the gauge. These were supposed to be Comp cams 918-16 springs. When he installed a new spring, not sure what kind but it was a behive it showed 100 lbs. The cam calls for 105 seat and 275 at 480lift.

Well theres more. When he was putting air in cylinder #8 air bubbles came out of the lowest head bolt closest to the fire wall! HUH......Thats where I'm at.

I'm trying to figure out what to do now. He'll prob charg me around $175 plus the springs and the heads still have to come off to fix the leak. He wants $500 to take off and install the heads. I could just get a new set of Sportsman II's and call it a day for $1500 installed and he will make sure it's all right.

Now my other delima....Will the Sportsman II ,72cc, 2.02 or the Brodix 180's, 70cc, 2.02 fit? I have a small .110 domed piston now. The heads I have atr stock 1.94 valves with 76cc chambers. Heres the piston.

http://www.camaros.net/forums/showthread.php?t=105300

68rs406
Apr 23rd, 07, 06:00 PM
Hmm, I mentioned valvesprings back awhile ago in the other thread about this, thats what it sounded like to me except for it being prominent in other cyinders more so. I kind of doubted it also because you didn't mention it popping like crazy as rpms increased. However, if your springs were that light it would definately run like crap. Who assembled the motor and heads?
The leak at the lower head bolt is odd, thats an odd spot for a head gasket to leak, and I thought those bolts where blind tapped, wierd, you did a leak down and it was good I thought?
Well, at any rate at least it's progressing, don't get too frustrated it will be worth it when its over :cool:

mnm99
Apr 23rd, 07, 06:12 PM
Hmm, I mentioned valvesprings back awhile ago in the other thread about this, thats what it sounded like to me except for it being prominent in other cyinders more so. I kind of doubted it also because you didn't mention it popping like crazy as rpms increased. However, if your springs were that light it would definately run like crap. Who assembled the motor and heads?
The leak at the lower head bolt is odd, thats an odd spot for a head gasket to leak, and I thought those bolts where blind tapped, wierd, you did a leak down and it was good I thought?
Well, at any rate at least it's progressing, don't get too frustrated it will be worth it when its over :cool:


Yea no popping or anything. I got this motor from a friend and just removed the 58cc 1.72 valve heads and put on a 76cc 1.94 valve head to bring the compression down. Before it was around 12:1. I'm figuring around 10:25.1 now.

Yea very weird.. but I saw the bubbles clear as day. He plugged in the air line and bubbles just kept comming from around the bolt head. Yes I did a leak down test and it came out fine.
Cylinder #1 = 4% or 96
Cylinder #2 = 2% or 98
Cylinder #3 = 5% or 95
Cylinder #4 = 3% or 97
Cylinder #5 = 4% or 96
Cylinder #6 = 5% or 95
Cylinder #7 = 2% or 98
Cylinder #8 = 4% or 96

Very weird!!! I'm sure it has someting to do with the gasket or maybe a cracked head?

I'm not sure what I should do with buying new heads now. Nobody can tell me if they will fit or not.

68rs406
Apr 23rd, 07, 06:34 PM
I don't know about the bubbles, that almost sounds like a cracked head, there should be no connection between the cylinder and that bolt. It could be an odd leak at the gasket from a deck imperfection, but ??? it's tough to say without checking them out, off the motor.
As for the heads, I can't think of any reason the SP II's or Brodix heads wouldn't work, the cam is mild, and they have a large old style chamber I believe (I'm 99% sure the sp II's do) so I doubt the dome would interfere at all. But, that said they always should be checked for piston to valve clearance and for dome interference in the chamber, but if your mechanic installs them it's his responsibilty to check. If I was a gambling man and was to guess about compatibilty, I'd say go for it, for what thats worth. (But please make sure and check or have them checked anyway ;) )

mnm99
Apr 23rd, 07, 06:53 PM
I just looked up the comp ratio now and It looks like around 10:8.1 with iron heads! This is a little high huh? Check out some calculators for me.

bore - 4.030
stroke - 3.48
Head -70cc (brodix) 72cc ( sportsman II )
head gasket -.039 4.125 bore
Piston -11cc dome
In the hole - .022

The Brodex are alum and the sports are iron.

Everett#2390
Apr 24th, 07, 04:54 AM
I've never been a believer of the stud/on-the-head spring pressure tester. If he's got air in the cylinder, he could have taken off the spring and checked it's pressure in a real spring tester, the anvil with a gauge and scale for height. Most stock GM springs are 100# at 1.8 inches.

The head gasket is probably leaking due to a loose head bolt or lack of re-torque after the iron heads are brought up to temperature and after cam break-in. Or as Sean suggests, the head or block are not flat. All the SBC head bolt holes go into the block water jacket. Iron heads get re-torque when hot, alum heads get re-torqued the following morning.

I know gasket technology has come a long way and most suggest a re-torque is not needed, but, I'm old school and learned from the School Of Hard Knocks, re-torquing is a good thing. The only bad part of a SBC is you have to remove the exhaust manifolds/headers to get to the lower row.

I get roughly 10.9 comp ratio with the Brodix heads. But, this is only static. Figure in the camshaft specs and find out what the dynamic ratio is. Remember, you can't make compression until the intake valve closes. Hmm, with a 280 camshaft, DR might be alittle high also.

The above are just my thoughts.

zdld17
Apr 24th, 07, 05:20 AM
Why dont you pull heads yourself? You have done a lot already so you should know how to do that. Based on what you describe the piston dome and your calculations, If this was a street motor , I would look at getting a larger comp chamber and get the compressiond down to about 10.0 or a tad under. I guess this is a street car. If you cant do that, pull springs and install a set of 981 or 986 comp at the recommneded installed height and be done. For sure 40# seat pressure is not gonna get it, and I always thought 90 was low. . Now you say that air is comming out of a bolt hole? we are back to what I suspected before, head gasket seal. Need to also check block where that gasket may be leaking, you could have already cut a nice little fire slot there.

mnm99
Apr 24th, 07, 05:34 AM
Why dont you pull heads yourself? You have done a lot already so you should know how to do that. Based on what you describe the piston dome and your calculations, If this was a street motor , I would look at getting a larger comp chamber and get the compressiond down to about 10.0 or a tad under. I guess this is a street car. If you cant do that, pull springs and install a set of 981 or 986 comp at the recommneded installed height and be done. For sure 40# seat pressure is not gonna get it, and I always thought 90 was low. . Now you say that air is comming out of a bolt hole? we are back to what I suspected before, head gasket seal. Need to also check block where that gasket may be leaking, you could have already cut a nice little fire slot there.


I know what your saying I could do it. I figured for $500 have him do it and worry about getting it right. If It doesn't run right I didn't do it. Besides the drivers side header has to be dropped to get to the bolts because of the PS box and to do that you have to lift the motor. I just don't want to deal with it anymore. Also the wife said she would feel better if he did it since I'm spending over a grand on heads.

I was looking at a similar piston as mine TRW-L2304F it has a 0.100 dome. Mine has a 0.110 dome. TRW calls this piston at...
355 CI
11:40.1 -58cc head
10:63.1 -64cc head
10:15.1 -68cc head
9.71:1 -72cc head

Why do the numbers look low? I'm not sure what the head gasket is also.

mnm99
Apr 24th, 07, 05:41 AM
I've never been a believer of the stud/on-the-head spring pressure tester. If he's got air in the cylinder, he could have taken off the spring and checked it's pressure in a real spring tester, the anvil with a gauge and scale for height. Most stock GM springs are 100# at 1.8 inches.

The head gasket is probably leaking due to a loose head bolt or lack of re-torque after the iron heads are brought up to temperature and after cam break-in. Or as Sean suggests, the head or block are not flat. All the SBC head bolt holes go into the block water jacket. Iron heads get re-torque when hot, alum heads get re-torqued the following morning.

I know gasket technology has come a long way and most suggest a re-torque is not needed, but, I'm old school and learned from the School Of Hard Knocks, re-torquing is a good thing. The only bad part of a SBC is you have to remove the exhaust manifolds/headers to get to the lower row.

I get roughly 10.9 comp ratio with the Brodix heads. But, this is only static. Figure in the camshaft specs and find out what the dynamic ratio is. Remember, you can't make compression until the intake valve closes. Hmm, with a 280 camshaft, DR might be alittle high also.

The above are just my thoughts.

He took off the springs and the came in at 64# max compressed! He brought them to the machine shop next door to double check thats why he was airing up the cylinder, then he saw that. The brodix are alum so I should be fine with 93 octane right? I was worried about the iron heads.

zdld17
Apr 24th, 07, 07:57 AM
You could use the steel shim with the 72 cc head and be safe as you said you are already .22 in the hole? Keep quench .35-.45. Steel shim prolly .017 or so. gitterdone.

Brian Lewis
Apr 24th, 07, 08:11 AM
Using your details I get
70CC Brodix - 8.76:1 compression
72CC Sportsmans - 8.59:1 compression

Looks like you are entering the data wrong into the calculator.
I would recommend 64cc heads with .015 Gasket - 9.8:1 compression !!

JimM
Apr 24th, 07, 08:28 AM
I just looked up the comp ratio now and It looks like around 10:8.1 with iron heads! This is a little high huh? Check out some calculators for me.

bore - 4.030
stroke - 3.48
Head -70cc (brodix) 72cc ( sportsman II )
head gasket -.039 4.125 bore
Piston -11cc dome
In the hole - .022

The Brodex are alum and the sports are iron.

On the subject of bad numbers, where did this come from?
I thought the other post determined that these were like PLUS 3.4cc?

mnm99
Apr 24th, 07, 08:38 AM
On the subject of bad numbers, where did this come from?
I thought the other post determined that these were like PLUS 3.4cc?


I talked to a person from badger and an engine builder that did alot with badger and they both told me 11cc and 11.1:0 . The TRW piston lists around the same numbers and are almost identical. TRW-L2304F .

TRW-L2304F
Bore (in): 4.000 in.
Bore (mm): 101.600mm
Piston Material: Forged aluminum
Piston Style: Dome
Compression Distance (in): 1.560 in.
Dome Height (in): 0.100 in.
Piston Head Volume (cc): -2.40cc
Valve Reliefs: Trough
Wrist Pin Style: Press fit
Pin Diameter (in): 0.927 in.
Top Ring Thickness: 5/64 in.

Notes: Approximate compression ratios: 11.26:1 with 58cc, 10.50:1 with 64cc, 10.02:1 with 68cc, 9.59:1 with 72cc, and 9.19:1 with 76cc head.

OK I believe you.

travis
Apr 24th, 07, 08:39 AM
Those pistons have approx a +3cc effective volume...not 11cc!! The pistons you have will make about 9.2 to 9.5 compression with a 76cc head, which isn't bad with the 280 magnum cam.

mnm99
Apr 24th, 07, 08:43 AM
NEW update....

I went home and for the heck of it I aired up #8 myself and did see bubbles. I got my torque wrench out and guess what...it was at 40lbs. I torqued it to 75 and the bubbles went away. ALSO...when the mechanic put my old springs back in so I can take it home until I find out what I want to do he put 2 shims under #6 ( the cylinder that was hot ) It brought the seat pressures to 70lbs. I got my temp gun out and that cylinder is now the same temp as the others!!! I think I'm going to retorque all the bolts and replace the springs and see what happens. It's weird because my leak down came out at 4% for #8.

mnm99
Apr 24th, 07, 08:44 AM
Those pistons have approx a +3cc effective volume...not 11cc!! The pistons you have will make about 9.2 to 9.5 compression with a 76cc head, which isn't bad with the 280 magnum cam.

Thank you.

Brian Lewis
Apr 24th, 07, 09:28 AM
Yep, better #s
+3cc dome, .039 gasket, .022 deck clearance
70cc - 10.12:1 compression
72cc - 9.9:1 compression
76cc - 9.5:1 compression

Everett#2390
Apr 24th, 07, 09:35 AM
NEW update....

He put 2 shims under #6 ( the cylinder that was hot ) It brought the seat pressures to 70lbs. I got my temp gun out and that cylinder is now the same temp as the others!!! It's weird because my leak down came out at 4% for #8.Cool !!!

So the winner is ?

mnm99
Apr 24th, 07, 10:30 AM
Cool !!!

So the winner is ?

I just talked to the mechanic and told him what I found. The loose bolt and good temps. The motor still runs a little rough though. I want to check the spring pressures and height before I pull these heads. remember Good leak down, good compression, no smoke , no blowing oil and all good plugs. I think there might be a problem with how the springs were set up. Theres no shims on any of them and the oil hood isn't there. My local engine builder said to remove the spring and see if I have 1.700 from the seat to the retainer. He gave me a small piece of rod that measures the right distance. He's betting these heads were set up wrong! My mechanic said pull the heads! $1600 for a head job or $80 for springs.??? i would retourqe all the bolts and get a new set of springs but he said I would be better off pulling the heads because bubbles shouldn't come from that bolt hole. But when I Retourqed it they went away.:o

zdld17
Apr 24th, 07, 11:36 AM
there is nothing wrong with setting new comp springs, maybe the 981 @ 1.7. But you need to know what pressure that installed height creates. Make sure your current retainers fit what ever new spring you select. Might install new keepers and if you have to buy new retainers, go the 10* locks and keepers. You will need a hand full of valve spring shims. Remember to try for shims with serrations on one side, they go towards the head. While you are at it, time to look at the valve seals. You can do all this with or without air. Remember Jims rope trick without air. I think you are almost done.
Wow, we are almost out of pages here.

dawg
Apr 24th, 07, 11:39 AM
well glad you found out the problems

mnm99
Apr 24th, 07, 11:54 AM
there is nothing wrong with setting new comp springs, maybe the 981 @ 1.7. But you need to know what pressure that installed height creates. Make sure your current retainers fit what ever new spring you select. Might install new keepers and if you have to buy new retainers, go the 10* locks and keepers. You will need a hand full of valve spring shims. Remember to try for shims with serrations on one side, they go towards the head. While you are at it, time to look at the valve seals. You can do all this with or without air. Remember Jims rope trick without air. I think you are almost done.
Wow, we are almost out of pages here.

The 981 spring says at 1.7 install height it's 105 lbs. I don't have a gauge to check it. The springs that are on there are 981's so all the restainers and keepers should interchange. I want to verify I'm at 1.7 now before I change the springs. Can't I just set them at 1.7 and leave it?

zdld17
Apr 24th, 07, 12:31 PM
ASSUMEing, these are new springs and I used these at one time, You could make sure your installed height is 1.7 and install . The springs that were on there when yu had 40#'s,, were they 981 also? Prolly set at a taller height too, no? Just trying to understand what went wrong with previous spring?

mnm99
Apr 24th, 07, 01:10 PM
ASSUMEing, these are new springs and I used these at one time, You could make sure your installed height is 1.7 and install . The springs that were on there when yu had 40#'s,, were they 981 also? Prolly set at a taller height too, no? Just trying to understand what went wrong with previous spring?

These are still the same springs. I didn't change anything yet.
ASSUMEing the person who did these heads installed the right spring. He told me it was a 981 CC spring. None of the springs have a shim under them either. I want to check the installed height and see where there at. It might just be he installed the springs as is with no shimming . If I install new ones at 1.7 would that be good? I was told I have to check the pressure too. I don't have a gauge.

zdld17
Apr 24th, 07, 01:15 PM
Understand what you been thru and trying to do. You could install just two and shim to correct height, If your problem is gone, then you know that you need to check all others. If your guy forgot to install shims in just two, what was keeping him from not doing it to others. This is why they make refried beans. Understand? Just wonder what could have happened to those 981 springs to cause them to loose their tension , something overheated? Did you guy install stockers or some other spring and keep the 981's . Never know.

Everett#2390
Apr 24th, 07, 01:23 PM
Got a bathroom scale, a 2X4, and an assistant?

Place the spring to be tested in the middle of the scale.
Place 2X4 on top of spring.
Place upper body weight onto 2X4.
Compress spring to the length of a wooden dowel or block of wood of 1.7 inches long/high/thick.
Read scale on bathroom scale. The resultant scale indication should be close to 100 pounds.

If you find installing shims under springs and the height is either too much (not enough shim) or too small (too much shim), go for too much shim, make the spring smaller than 1.7 inches. A few thousandths of an inch won't matter.

Replacing stem seals is easy. Probably get a pack free from the local head shop if not for a few bucks. Use petroleum jelly as a lube to seat the seal in the groove closest to the head, install retainer, then install the seal, then install the keepers, slowly release the the spring.

72Tugboat
Apr 24th, 07, 04:01 PM
Unless you use the stock metal shields, those little o-rings don't do much. They do keep oil from running down between the locks, but without the shields it's pretty moot.

Better to use some umbrella seals unless you have double springs (the flat damper is not a spring). If the heads are machined for positive seals they would be a good option too (nessecary for double springs).

Good Luck!

68rs406
Apr 24th, 07, 10:32 PM
Cool !!!

So the winner is ?

He He, I posted this back on april 12th in the IR gun thread regarding his temp questions
I don't know what to tell you, you've done everything almost, the one thing that keeps popping up in my mind is a bad valvespring, either broken or just dead, the only way it would show up is running funny (does the miss get worse at higher rpm?) or testing the spring, compression and leakdown wouldn't show it.
Obviously you have the cylinder pinpointed, you are just going to have to start taking things apart and looking close at everything. I would try checking your valvesprings first, you can do that with everything assembled still.
Was I the first to mention it? If so what do I win? :D :)
That was the only thing that made sense after all the tests, the one thing that wouldn't show on a leakdown after ignition was checked out.
The reason the leakdown missed the leaky/loose head bolt was it was a minimal leak, just enough to show some bubbles.
Good deal, I think you have it! :thumbsup:

lortsie
Apr 24th, 07, 11:26 PM
Thank god now I can sleep! LOL j/k glad we found the culprit.

zdld17
Apr 25th, 07, 03:18 AM
Does this thread quailify for the longest? Prolly not.

mnm99
Apr 25th, 07, 04:06 AM
Thank god now I can sleep! LOL j/k glad we found the culprit.


This thread is not over! The car is still running rough. He told me it's the springs, But this guy also told me it was the ignition if you remember a while back.....Untill this thing is running right nobody wins! The heads will have to be taken to the real judges, my local enging builder to determine who the winner is.

zdld17
Apr 25th, 07, 05:01 AM
This thread is not over! The car is still running rough. He told me it's the springs, But this guy also told me it was the ignition if you remember a while back.....Untill this thing is running right nobody wins! The heads will have to be taken to the real judges, my local enging builder to determine who the winner is.


Have you changed that one set of springs yet? Like I said before, if just those two are weak, I would suspect they all are. Agree, heads can come off and see thats in them and the deal with that leaking head gasket at #8. As you mentioned, if you feel you will be sinking lots $$ in old heads,, you need to make a good decision here.

mnm99
Apr 25th, 07, 05:42 AM
No I didn't change them . last night I measured the spring height kinda.. My engine builder cut me a 1.7in rod to measure my installed height on the spring. All I ended up doing was measuring the top of the spring to the head, not even into the spring pocket and it almost came out to be 1.7! I bet something happened to them and because it might be on the edge of the installed height something just happened. None of these springs have shims under them also. I don't know.
I'm very frustrated right now! I don't know what to do.
I could just try to replace the springs and see if that works. If that doesn't do it I would have to pull the heads. Now the mechanic wants $500 to do a complete head swap with my parts or I can do it myself. The problem is, If I pull the heads I want to get a new set. The thing with that is the piston I have is a Badger P552 0.110 domed piston and no manufacture will tell me if there head will fit. I don't want to spend the money to pull them and more to fix the old ones and have the same stock head performance out of all this. It will cost me around $350-400 to freshin up my heads with new springs or $1000 fro new Alumunm (sp) heads. :( :(

I'm no expert with the clay thing and what to do. If I knew the brodix or world heads would fit I would do it myself. The mechanic is going to talk to someone he knows. If he says yes then I'll make him responsible for the fit i guess.

zdld17
Apr 25th, 07, 08:13 AM
Why not pull them yourself, save $500 towards new set of head. You said you can do it. I would. As for the specifics of your piston, If you know what you have, you should be able to get a head to match, IMO , you are only looking at either 72 or 76 cc. Jim questioned numbers you put out, make sure that you piston domes are correct then go from there, but you still have not verified if the higher pressure springs will cure your problem as well as the possible leaking head gasket.

All those in favor of Marc doing the job himself, say Aye!


Aye!

Everett#2390
Apr 25th, 07, 09:21 AM
Aye!

lortsie
Apr 25th, 07, 09:33 AM
Aye! You've done some good work yourself so far - you'll feel a lot better about having to spend any more dough if you know you did what you could yourself!

68rs406
Apr 25th, 07, 08:44 PM
Aye! No time to start learning like the present, besides, it's a piece 'o cake :thumbsup:

Joe Harrison
Apr 25th, 07, 09:25 PM
Aye!!!

What you have done and gone through, changing heads will be a pice of cake even if you have never done it before.

Now I know we all went from one end of the spectrum to the other on your problem and helping to try and figure what the heck was going on. You took lots of advise and kept on going and you still have not just said screw it and have some else do the work!!

Don't stop now, you have come along way baby!!! You can get tools that will will verify spring pressures and installed hights etc on your set of heads and do them yourself and reuse the heads and just be out the cost of a set of needed tools and some gaskets plus your labor. You will use the tools again even if it's ten years down the road you will have them.

Next option is to get heads that have a chamber to accept your piston with no troubles and verify the fit before final assy with clay. It's really easy and I suggest the book "how to build your small block Chevy" for this project. It's an oldy but a goodie!!

next option is to pay the mechanic to do it. To me this is a complete waste of money since you have the ability to do it yourself and if you have the cash to spend, then spend it on upgrades to the engine or someplace else on the car. You could also buy a nice meal, hotel room and a sporty rental car for week end for what that dude wants and you would be treating the wife or GF too. That part works out great because you get your Camaro where you want it and score points also..........double/triple bonus and weekend of play...........wahhh hooo.....

First thing I would do before anything else is Buy that book. You can do it, you have done all this and TC is still here to help also.

Joe

mnm99
Apr 26th, 07, 02:22 PM
UPDATE... http://www.camaros.net/forums/showthread.php?p=771900#post771900

68rs406
Apr 26th, 07, 05:52 PM
So what do I win? :D .
Congrats, I have no doubt thats your problem. :beers:

mnm99
Apr 26th, 07, 06:09 PM
So what do I win? :D .
Congrats, I have no doubt thats your problem. :beers:

I sure hope so, but I thought weak springs would cause missing at higher RPM's. I never had any missing or popping at higher rpm. Only missing at lower. So far everything I've been reading nothing mentions lower RPM problems. But who knows 50lbs at seat may cause that....I sure hope it's it.

zdld17
Apr 26th, 07, 07:25 PM
Just think of that valve bouncing on the seat at hi rpm? :eek: Maybe you had enuff to try to slam it shut but at low rpm, it just was not closing quick enuff and never sealed.