I decided to post this on it's own to see if I could get some other responses. It was an update to this posting:
http://www.camaros.net/forum/ultimatebb.php?ubb=get_topic;f=17;t=000895

I just got through doing a compression test on my car.. The news is not so good.. Here are my results:
#1. 240 PSI
#3. 235 PSI
#5. 240 PSI
#7. 230 PSI

Now the bad part..
#2. 75 PSI
#4. 58 (or so, needle only has increments of 5)
#6. 70 PSI
#8. 60 PSI

This all started after the most recent incident where the car was pinging and I stupidly put my foot into it. The car did stop pinging once the secondaries opened, but obviously it was only the roar of the engine drowning out the bad sounds.

Now my questions. What would cause every cylinder on one bank to read so low, while the other bank of cylinders is right where they are supposed to be?

Not that this is relative, but when I pulled the header on the passenger side, the #2 exhaust port is COVERED in oil.. It was literally running out of the port when I pulled the header. The inside of the pipe was also covered with oil, and showing signs that this had been occuring for a while. So, either rings, valve seals, or intake gasket leaking on that port??????

Also, there are little puddles of oil on TOP of the intake manifold on the bank with the low readings. Every intake manifold retainer bolt on the even cylinder side is buried in a little pool of oil.. This is all very strange..

Tomorrow I will pull the head on that side, and see if I can figure out what the heck happened. I find it hard to believe that a head gasket would go bad between all four cylinders at once.

Any ideas as to what could have happened?
Thank you!

I don't have an answer to all your questions. I will say that oil in your combustion chamber would increase your chance for detonation. With this in mind that could be what caused your problem to begin with. If you figure out the source of the oil in the cylinders you will prevent this from happening in the future. If we assume that the oil in the cylinders caused or magnified the detonation, and that would explain why those 4 cylinders went south. Detonation is not something to play with (as you can see) the low compression readings could be from collapsed/broken ring lands in the piston, caused by the detonation, which in turn could have been caused by an oil leak into the cylinders. Since you do have some compression I doubt you busted a hole in the piston but, they (the pistons) are probably still toast. When you disassemble it make sure to be very careful and see if you can figure out where the oil came from (intake gasket, valve seals, etc..). I don't know the history of your engine (ie..how old, miles, compression). I think when you figure out the oil situation you will have found the cause of the whole problem. Did the car smoke at all (leading up to this)? There is a good chance your bearing got hammered as well. Pay close attention to your small end bore of your connecting rods as well. Detonation really puts a beating on these parts.

In the other thread you mentioned the temps were 20-30 degs out when this hapened and you blew the dipstick right out of the tube... What percentage of antifreeze were you running?

Dennis,
I am running a 50/50 mix of anti freeze and water. The temperature on that night was no where near freezing. It was probably mid 50's or so. It was a drop from the high 70's low 80's that we were having just prior to that.

I have been thinking about this and have decided to do a cooling system pressure test when I get home. This should help me determine if it is a blown head gasket, or cracked block or head. If it is just a blown head gasket, I will change out the head gasket and then try a new compression test to see where that puts the readings. If they are still down, I will tear into the bottom end.

Is there any test that I can perform right now to test the rings on the #2 cylinder? I believe the rings to be OK, but want to rule them out. I am almost certain that the intake manifold is not sealing and that is how the oil is getting into the #2 cylinder. One of the replies above asked if the motor was smoking before this. I have true dual exhaust and it was puffing very lightly from the passenger side (#2) side. Not much, but you could see a little blue ring puffing out. Now I know where it was coming from. The reason I think the intake is not sealing is because I had to have it cut to work with the heads. The heads were angle milled when I bought them, and I did not figure this out until I tried to bolt on my intake. After taking the intake to a machine shop to have it cut, it was still work trying to get the bolt holes to line up but the machinest assured me that it would seal.. This motor has less than 5,000 miles on it since it was put together.

Some of the things that I am still pondering. If only one cylinder was detonating-why did the other three on that bank lose compression as well?
Why is there oil on top of the intake, but only on the bank of cylinders with the problem?

My plan: 1. Cooling system pressure test!
2. Remove intake and check for oil tracking past the gasket into the #2 cylinder.
3. Remove passenger side head. Replace both valve seals for the #2 cylinder.
4. Inspect pistons, bore, and head for obvious signs of damage.
5. If no obvious signs of damage, replace head gasket and do a new compression test.
6. If compression tests ok, purchase new heads and intake.
7. Regardless of what happens--Replace current 160 thermostat with at least a 180 or higher!

Did I miss anything?

You can't always hear detonation, so don't assume just # 2 was rattling. Now that you mentioned your intake sealing problem, there is a very good chance that's where your oil came from. How did the machinist know what angle or how much to cut the manifold without the heads? I don't know if I would trust, that the manifold would seal. I am sure you could get it to seal with the aid of some typw of adhesive.

If your compression it that low I don't think there is any use in doing a leak down test, that would tell you if your rings were bad (or if pressure/compression was leaking out anywhere). If your manifold was not sealing properly that would/could create a lean condition as well that would increase the chance/amount of detonation, that along with the oil leak could have caused your problem.

Did you torque the manifold down in the proper order? Sounds like it may have been pulled over to the drivers side a little. If it fit properly that should not have been easy to do. Good luck.

[ 12-02-2003, 10:42 AM: Message edited by: camaroman7d ]

All of your low numbers are on the right bank. I would look for something this bank has in common, i.e. manifold leak at head, head gasket, etc. It just seems weird that the left bank is solid and the right is kapute.

The intake gasket should not effect compression readings.

FWIW compression readings on the "good" bank are pretty high. Too high for pump gas IMO.

When I broke my #2 piston ring land last summer, the cranking pressure was down around 175 psi in #2 --- the rest were at 210-215 psi. The second compression ring will hold enough to build pretty good pressure when cranking the engine even if the top ring is busted up pretty good.

My bet is a massively blown head gasket and possibly a broken piston or two . . . something has to be MAJOR wrong to have compression readings that low in an entire cylinder bank.

Update: I did the coolant system pressure test and it held a steady 16 PSI without dropping for over 3 minutes. I was afraid to pump it up any more as I did not want to cause any leaks anywhere. I also tested the cap, and it checked out fine as well.

I now have to remove the head to check the physical appearance of the components.

Is there a way to tell if the rings, or ring lands are broken while the piston is still in the bore?

If the top ring land is collasped, broken or cracked, you should be able to see it. Also check to see if you can rattle the piston around in the bore. Don't overlook bent or warped valves. If I had to guess I would say the pistons are damaged in some way. You can also add a little oil to the cylinder and try your compression test again. This should raise your numbers some if it is a ring problem. In either case with readings that low you will have to open it up. Let us know what you find.

sounds like the head bolts weren't torqued properly on the low comp head,maybe not retorqued?
Eric B

God point sleeper. The only thing is if the head was that loose I would expect the pressure test to have failed. Maybe not, it would be great if it is something simple like that.

The rebuilt 265 that was in my '55 Belair H/T had two different heads on it, but since it was a two barrel, P/G combination, I never worried about it but did notice that it didn't run smooth b/c, I assume, the difference in the CR. per bank.

Carried to the extreme this could blow a bank of cylinders up like you have done..?? ..

pdq67

Update:
I pulled the head and inspected the piston, the head itself, the #2 bore, the head gasket, and the intake gasket. I can see no physical damage at all. No signs of valves hitting the piston, no signs of a bad head gasket, no signs of oil leaking past the intake gasket.

I did find that the valve guide seal on #2 intake had come free from the top of the guide, and was riding up and down inside the spring. This was where the oil was coming from. Upon removing that spring/valve, I found that an aftermarket guide has been pressed in, and it mic'ed out at 0.502".

The seal is aftermarket with a metal band around a white plastic/teflon??? I simply tightened the band by squeezing it with pliers and then re-seated it on the guide. It is much tighter now and seems like it will now stay in place.

I cleaned the head up, and the bore, and put it back on along with a new head gasket. I replaced the rockers, and the push rods for #2, and did another compression test. I now come up with readings in the 90# PSI range. Do new perma-torque gaskets need to be run in, or heat cycled in order to properly seal?? I don't know if my test would be valid if they need to be heated up to properly seal. Regardless, the 90 PSI is up 15 PSI over the first time I did the test.

In looking at the bore, it is mirror smooth and shiny. I could not detect any scratches as I think would be present if I had broken rings. No cracks on any of the piston tops. Nothing evident as to why those cylinders are low.

What should I do now? Should I pull the motor and then pull those pistons out of the bore to inspect them?

I have pictures of the bores, the pistons, the head, the head gasket if anyone would care to take a look at them. I can either e-mail them, or post them on one of the free hosting sites.

Thanks for helping me up to this point. Is there anything else I can do before pulling the motor and disassembling it??

It would be great if you could do a leakdown test.
If you don't have a leakdown tester, buy an "air hold" fitting. It's like a sparkplug drilled out with an air hose attached to it. Air pressure is put into the cylinder to hold the valves closed, when using a valve compressor tool to remove valve springs with heads on the engine.

Anyway- use this tool or if you have a hose for a compression tester of the type that screws into the spark-plug hole, use it to blow air into the cylinder and listen for where it is coming out.
The piston should be at TDC when you do the test.
If you hear hissing in the crankcase, you have a ring or ring land problem.

If it's a bad valve, the intake or exhaust will hiss.
David

I would try what David suggested, that is excellent advice. Did you try putting a little oil in the cylinders when you did your last compression test?

Ok, to answer the questions, no, I did not put oil in the bore when I did the compression test. I cleaned out the bore, and vacuumed it to insure that there was no sand or grit in there for the test.

I do have a compression tester, and could use the hose for that test. Bad news is, I already pulled the head as I needed to get it cleaned up. I guess I can bolt it back on today, and try the air pressure test.

Will post back to let you guys know what I find. When I was cleaning the heads up yesterday, I attempted to pressurize the intake ports, and the exhaust ports with the garden hose to see if the valves were leaking.. There was no water getting past the valves at all. They all held the water pressure without leaking. Unscientific test I know, but I think that if the valves were not seating well, I should have seen some water escaping past the valves..

Going to the garage now. Will post back later today.

I went to the garage and bolted a head back on, torqued it to 65 ft. lbs. and went about the test. I tried using the hose for my compression tester, but it would not work. It took me a while to figure out that the shrader valve was stopping the air from reaching the cylinder (duh!). I then removed the shrader valve from the hose and PRESTO! I can now hear an ocean of air escaping into the crank case! I tried each cylinder on even side bank, and it is always the same-lots of air rushing into the crank case.

Looks like I will be tearing it down to figure out what has happened. I expect to find cracked rings, or destroyed ring lands.

Will post back later..

Sorry to hear you have to tear it dwon, it does sound like it is the rings. Your heads seem fine. Since you did have detonation, there is a good chance the ring lands collapsed just enough to trap the ring. Since your cylinders aren't scratched you souldn't have too much work to get it back together. Maybe a hone job and a set of pistons, ring and bearings.

In the words of my life long mentor, "I say, I say boy, something just don't add up."

You should have seen something obviously majorly wrong when pulling everything apart. I have never personally seen an entire bank of cylinder go bad like that . . . ever. Its almost like someone forgot to put rings in the pistons or something.

Are you sure your gauge is good? could you have dropped it between banks? Maybe you could do a quick check on the other (good) bank as a control experiment.

Sorry for asking dumb questions, but something is weird here.

I agree with what you have posted Eric68. The one thing that sticks out in my mind is that the heads were angle milled long before I got them. Perhaps one head was milled more than the other, causing higher compression on that bank of cylinders.

At this point, I am tearing the motor apart, and checking/replacing the pistons, rings, and associated bearings throughout the motor. I am selling the heads, and intake as a set. Hopefully someone with a motor with lower compression can take advantage of that deal. The intake has already been cut for those heads, and after tear down, I could see that the intake was sealed properly, and the coolant system pressure test showed that there were no leaks at the water ports.

At this point, I am looking for a good set of 76CC chamber heads, and a new intake to try and compensate for the compression that I am at.

Once I get the motor torn apart, I will take pictures of the pistons, ring lands, and rings, and post them on Hobbystage.

Thanks for the input so far.

So did you ever figure it out?

No. I still have not torn into motor yet. I have been busy gathering the parts that I need to rebuild. I don't like to start projects unless I have ever nut, bolt, part, piece, and gasket on hand in advance. The short block is sitting between the frame rails waiting on me.

I have purchased another set of heads (in shipping), and new dished pistons, rings, and an engine gasket set. The pistons are 12.5 CC dished, and my heads are the Corvette aluminum cast #113 heads with the 58 CC chamber. As near as I can tell, this will put me close to 10.20:1 compression ratio which is less than I was running before.

If anyone has a link to a compression ratio calculator, I could use it at this point.

Well hang in there, just let us know what you find, cause I keep wondering what might have been the problem.

I think your Corvette heads and -12cc pistons will work nicely in a street motor. I get 10.21:1 static compression with a .040 deck height.

Just search for any post by Pat Kelley here or at Team Chevelle, there is an excellent calculator you can down load from his site. Just look for the link in his sig.

PS. Here's the link to Pats home page. If you scroll down to the bottom you can click on the download links. http://members.uia.net/pkelley2/DynamicCR.html

Just a question but was this a fresh rebuild with 5000 miles on it? Did it smoke and rattle since day one? It sounds like to me that the finish bore dia was to big ( .030 over bore piston with a .040 bore block only on one side). Was this checked for piston wall clearance? You also said the cylinder walls are very smooth with no scratches. A bore with a hone job should show hone marks well after 5000 miles unless the piston has been slapping arround in there.

I would check the finish bore dia and the piston dia and see what clearance you have after its apart just for giggles.

Also angle milling the head and NOT correcting cut the intake face will not seal! You are now making the intake face a new angle that dont match.

Eric,

So your mentor is "Foghorn Leghorn??

He, He!!! I just had to...

BTW, maybe the rings are put on up side down??? I just donno....

pdq67

This was a recent build. The motor since build has less than 5,000 miles on it. When I said the cylinders look good, I meant that there are no obvious signs of damage. There is still a definite cross-hatch pattern in all 8 cylinders.

The car did smoke from day one, but ran very strong with no signs of serious problems. Now that I have had the heads off the engine and sitting on the bench, I have noticed other intake valve seals are up and off of the valve guides. I have found one so far that has been crushed. The exhaust valves have the plastic mushroom type seals, and all of them are riding high up against the retainer.. Why? I don't know..

The pistons and rings were brand new when I assembled the motor. The rings are file fit and all of them were gapped at the proper spec. The pistons were given to the machinist for the hone work, and they sit very tightly in the bore. You can't rock the piston, or move it side to side at all. If you can, the amount is so slight that the human eye can't detect it, and you can't feel it with your hand.

Rings upside down? If I were to have screwed up that bad, I think I would have been more consistent and the other side of the motor would have been affected, or random cylinders would have been affected as opposed to just one side.

The intake was milled on the sealing face and the ends to mate properly with the heads. There was no evidence of oil or water leaking past the intake manifold mating surfaces as the coolant pressure test showed no leaks, and there was no tracking of oil on the gaskets. There was a very crisp impression on the gaskets from the face of the intake on both sides. No sealing issues there.

I have no idea what has happened. I will post back once I get the pistons out of the bore. I have a feeling that the damage will not be evident, and that I will have to look deeper for a cause. This happened right after pressing the motor pretty hard through multiple gear shifts.

I also thought of the upside down rings scenario.
Pretty odd situation.

I don't think it could be rings upside down. That wouldn't effect cranking compression that much, although it would probably cause oil burning and a loss of power.

When I broke a piston ring land I lost about 1-1/2" of the top compression ring and my cranking compression only dropped to approx 150 psi from 215. I suppose the second ring was holding most of the pressure.

I saw a bent exhaust valve that only dropped the cranking compression by 30 psi. There has to be something major wrong here . . .

PDQ67, yes, the wisdom of Foghorn Leghorn is tough to beat ;)

UPDATE! I finally got the motor pulled and disassembled today.

I would like to pose a question, and then you must guess the answer before looking at the pictures... Here is the multiple choice question:
In the end, was it a cracked/broken block, rings, or pistons?

Now go here: http://www.villagephotos.com/pubgallery.asp?id_=600153

for the answers.

I do have another question, look carefully at the color of the #2 rod.. it looks rusty? Any idea as to what might have caused this? None of the other rods are discolored like this. Once removed, the bearing shows no abnormal signs of wear, and the crank journal shows no damage either..

Without looking and by your description of the rod I would say cracked block.

Without that description I would say broken piston (also from your previous posts).

Edit* And after all that I was still wrong, LOL.

Was that rod was the same color as the one next to it when you installed it? (strange).

Were the ring lands colapsed on that side of the block (kinf od hard to see in the pictures). Was the block hurt?

Maybe I missed something in the pictures, but I have to say the answer is d) all the above. I saw a piston with broken ring, a piston with collapsed ring land, and a rod that looks rusted.

The collapsed ring land(s) would explain low compression if you have 4 pistons that look that way, but what caused the ring lands to collapse? Is the collapsed ring land(s) just a symptom or the problem? IMO the answer may lay in the rusty rod.

Rust will usually only happen on a rod like that in the presence of water --- so could you have a cracked block, cracked head, or blown head gasket that allowed water to get into the cylinders? Water of course won't compress which would in turn break ring lands.

The other possibility on the discolored rod is that it got really hot from a spun bearing, but based on my experience usually they turn blue and bend. They might rust easier when exposed to air after being overheated, but I don't think that is what happened here since you said the bearings all looked OK.

Thanks for the follow up

I think that the copper color is the a factory coating that was used to resize rods that weren't quite right. It is no problem at all.

I'm with Phel69 here, that "rusty" rod is not rust at all and is not the problem.

How many pistons and or rings were bad?

Just fyi, if you are wondering why you are not getting notified of replies via email, they are all bouncing back.
Must be time to empty the ol mailbox

SMTP error from remote mailer after RCPT TO:<poolstuff@juno.com>:
host mx.lax.untd.com [64.136.28.83]: 554 poolstuff@juno.com Mail quota exceeded

Al, thanks for the heads up. Problem fixed!

In regards to the motor, all four pistons (2,4,6,8) have exploded ring lands. When I say exploded, I mean the land between the #1 & #2 compression rings fall off the pistons as soon as I pulled them from the block. There is just a little strip of aluminum left that supports the top of the piston to the rest of the piston body. The rings did their job and none of them cracked, distorted, or broke.

Those pictures should be shown to anyone that chooses to run 11:1 or greater compression on pump gas.. It just does not work.. Even when mixing octane boost and running premium gas, with reduced timing.

Check the ring ends (where they are gapped) and see if any of them are shiny. If they are then they butted up.

If the rings were not properly gapped (too small) when they expand from the heat they butt together and tighten up in the bore. This can/will knock the lands out of the pistons.

Bob.

I'll have to disagree - you CAN run 11:1 compression and pump gas if you set your motor up properly. I've run 11.3:1 for a while with no problems. An inspection in December revealed that all my pistons were happy.

To run a high compression ratio in a street motor you need to have an efficient combustion chamber, with good quench and enough cam to bleed off some cylinder pressure. cool air temperatures and cool water temperatures are also important. IMO 11.0-11.5:1 is about max with aluminum heads and about 10.5:1 is about max with iron heads.

ttt..

Were the rings butted?????

pdq67

Sorry to hear about your troubles!

Just out of curiosity, what cam and heads were you running? Was this a 383?

Hypereutectic pistons by any chance?

Thanks!

To answer the questions posted above, no the rings were not butted. The ends where they meet are not shiny or colored, or otherwise disfigured.

Yes this WAS a 383 with flat-top Powerhouse pistons. I think they are generic cast pistons. They are paperweights now.. I was running 186 casting, double-hump heads that had been angle milled. I have no clue how many CC's they were as installed. I would have to guess that at least .060" was taken off the combustion chamber side. The cam was a .465/.488 with 224/234 deg. duration at .050" on a 112 LSA. Nothing radical, just a good torque cam.

I am now in the process of re-building the engine. This time, DISHED hypereutectics, and aluminum GM heads, with a Comp Cams XR288-HR10 hydraulic roller cam that I will be using solid rollers on. I believe (off the top of my head) the numbers are .520/.540 with 236/244 deg. duration @ .050". on a 110 LSA.

Things have been moving very slowly because of lack of funds. I sold the old heads to buy the aluminum heads, and now I am saving up for the pistons. Once I have the pistons it will go back together very quickly. Just a matter of time. Hopefully I will get some money back for income tax, and then I will be set.

I have heard of people running solid lifters on a hyd roller before (during the lifter shortage). I am curious as to why you would want to do that? The solid lifter is lighter I know that, but what else do you gain by doing this?

A couple of reasons. You can run higher spring pressures without fear of collapsing the hydraulic lifter internally, solid lifters are MUCH lighter, and you can use standard length push rods. Plus, I have heard that you don't need to adjust the lash as often when running the SR lifters with HR cam.

Plus, I inquired about this once before, and there are a few members that post here that have been running their cams this way and have had no complaints. That further encouraged me to go this route.

Just do lots of research before you go that route (HR cam with solid roller lifters). I have heard that the ramps on a hydraulic roller cam are very short and much more agressive than on a solid roller cam. This makes it hard on valve train, but have not personally tried it so I dunno for sure.

ps. why not just get a solid roller cam?

Why not get a solid roller cam? Because I don't want to have to mess with adjusting the lash very often. Plus, I got a screaming deal on the cam that I could not pass up. I know I could probably sell it, and then use that money to get a solid roller BUT this cam already has a pressed on iron distributor drive gear which most solids DO NOT have.

I am running a high volume oil pump and want to avoid the hassle of switching out the oil pump due to mellonized, or bronze distributor gear wear if I were to run a solid roller.

I would just put a hydraulic roller lifter on it then you never have to adjust the lash.

That is an awesome cam, but you will never need to spin it higher than 6000 RPMs so you don't have to worry about float from the heavy lifter.

Also, if the cam is like the current ones, it's heat treated iron, not billet. If you up the spring pressure like what is used on solid roller cams you risk destroying the cam (it's too soft for that much pressure). It's just not worth the chance. You may save $80 for new pushrods but things will get a lot more expensive than that if something goes wrong.

I really don't see how running a solid roller lifter on a hyd roller cam will make the lash adjustments any different. How will you know what to set your lash at?

Eric,
You said exactly what I was thinking why not just buy a solid roller. I know you can get a solid roller with the cast iron gear (Crower makes them for example).

If anything I could see going the other way araound putting hyd rollers on a solid this would eliminate valve lash adjustments.

After all it is your car do what works for you. Let us know how it goes maybe we are missing out on a hot set-up. I understand you got a great deal on the cam, just do your research before you end up spending even more to fix something that got ruined.

If you put solid lifters on a HR cam you should in theory have to adjust or at least check lash MORE often. The reason being is that the HR cam has very short ramps and when using a SR lifter you have to hit that small ramp exactly - no margin for error like the SR cam with much bigger ramps.

Hope that makes sense.

PS. Just read an interesting article in Super Chevy about putting HR lifters on a SR cam. They actually made MARGINALLY more power with the HR lifters, although it was an under 6000 RPM grind . . . talk about a head scratcher. :confused: