In simple terms, the problem is:

At RPM's BELOW 900RPMish, THE ENGINE WILL STALL OUT.

(i'll add as much info as i think of it)

1)The engine is a stock crate 350, no computers, stock quadrajet, stock hei ignition.

2) (i'm pretty sure that) the idle speed screw is not the problem, but i'm willing to "test" this if nessesary. As an additional note when the truck was running normally, which was only 5 days ago, it idles at 500-600rpm in gear.

3) i need to give the engine gas to keep it running and the engine runs ok at 1000 or above.

4) at rpm's below 900, the idle is very rough to the point where the engine barely runs, and of course, eventually stalls---it does not matter if in gear or not.

5) the engine ran just fine up until last week which is when the symptoms started---the symptoms actually started in mid-commute.

6) The distributor did not move----i could not move it by hand. Thus, i thin k we can safely assume that the timing did not retard. (?)

Again, there's probably much more info that i can't think of at this time but will add as it comes to me or as it comes up when we discuss the issue. Such as, i've got at least 2 TVSes (thermal vacuum switches that control EGR and vacuum advance, just to complicate matters a bit).

Vacum Leak

Trash in the carb or vaccum leak or hose off???

Egr valve stuck open?

Hi - maybe you could take a second and include your name and where you are located. This will help in a couple ways, one it will give everyone a clue to the winter weather conditions you may be in and the other your screen name is a bit silly for folks to be saying "Hi puff puff" when replying to you.

Hey speaking of information, how about a clue to what year vehicle we are talking about? I have no idea why you chose a 1st gen Camaro forum to ask about a smog equipped truck but I know the guys will be glad to try and help if they can...

Adjustments like timing and carb settings (mixture screws as an example) don't just turn themselves so resist the urge to try changing settings and making adjustments to resolve this. Use a timing light to see if your timing is where it should be. Your dist may not have moved but it you have a bad timing chain it will effect the timing. Look for vacuum leaks and if you have cats maybe they are plugged and need replacing. Did the weather just change? Maybe it's a choke that has never worked and now the cold weather is causing it to be messed up. Anyway just more to think about...

1) the EGR:
i'm not exactly sure how to test it, but actually before that, my service manual said that there are two types of EGR---positive and negative and the manual wasn't clear at all.

i took this one off the engine:

http://i223.photobucket.com/albums/dd31/sencraig/100_0412-1.jpg


And, this one i took off of a 305 engine that is laying dormant in my garage just for comparison purposes:

http://i223.photobucket.com/albums/dd31/sencraig/100_0413-1.jpg

Now, how in the world do tell which if they are positive feedback or negative feedback whatever that means?

a) As an additional note, for the top one, i was able to push the diaphram in all the way and put my finger over the place where the vac hose would go and the diaphram would stay inwards until i released my finger and then the diaphram moved back to resting position. If this makes a difference.

2) i think puff puff is a cool name, but if anyone feels "awkward" about it, maybe you could call me p.p. i suppose that may be worse?

a) North and it has gotten a little colder, but not that much and i don't think that is the problem, because it was 60 degrees yesterday, and the problems still persisted.

b) and yes, it is a truck, 83. And the reason why i'm on a camaro site, is because we basically have the same engine drivetrain setup---as do most chevrolets from 55-to about 87ish. i'm basically trying all related sites, not just camaro. At any rate i know camaro people are very knowledgeable about these things. Also, i have owned 3 camaros and will very probably own another one soon (2 gen). i hate the 5th generation and i feel that kind of approach towards carmaking is one of the reasons why gm sucks today. Anyways......

3) i totally agree with idle speed and timing and that's the reason why i want to try the other vacuum related stuff first.

What were you doing exactly when the issue 1st presented itself? I am thinking, if not a vacuum leak, that you may have a head gasket issue or intake gasket issue. Have you ran a compression test on it or pulled the plugs? How does the antifreeze and oil look? Milky?

Hey puff puff, from "some lame planet!":D:hurray:, how you doin? and, welcome to the club man!:thumbsup:.....Are you smellin any kind of a lean smell coming from the exhaust? as I suspect a carburetor related issue!.....Is it poppin or anything out of the carburetor?

1) i was in mid-commute when it first started occuring. And the first thing i noticed was that it took much, much longer to switch from 2nd to 3rd (it's a th-350C, thus only 3 speeds as you proabably know) usually it will switch, with the way that i drive, into 3rd at about 1900-2000. This time it took to about 2400-2500 to go into 3rd at probably above 47mph. i didn't think much of it at the time---probably needed more fluid or so i thought. Next when i started to slow down to get on the on-ramp, it started to shudder real bad with the vacuum gauge making very broad sweeps across the whole dial. The only way i could make it to the office was to just before getting to a stoplight/sign is to put it in neutral and rev it up to about 1200 rpm. When the light turned green i would put it into drive at a little/lot higher than normal rpm which probably wasn't real good for the drivetrain but i was able to get moving without stalling. At speeds above, say, 1200rpm or so, the engine ran ok, maybe slightly a little rougher than normal but nothing to real complain about.

a) i haven't done compression yet, but that's a good idea. i haven't checked plugs, oil or antifreeze yet.

2) i'm not really smelling leaness, if anything a bit of slight richness. No popping. i'm guessing that maybe, just maybe the filter needs to be changed. But other than that, i'm thinking vaccum or ignition, because when it's running rough, the vaccum gauge makes broad sweeps accross the whole face of the gauge in rhythm with the engine.

1) the vaccum gauge makes broad sweeps accross the whole face of the gauge in rhythm with the engine.A good indication of a faulty carb in fuel delivery. Dirt in an idle orifice, etc.

1) the vaccum gauge makes broad sweeps accross the whole face of the gauge in rhythm with the engine.

This makes it sound like clogged exhaust...

Right! So i'm thinking (hoping) that it might be that flapper door thing on the right side exhaust manifold(i still have the origninal-stock manifolds).

Too much fuel as in trash on the needle valve or a vacuum leak-especially with the shifts taking longer. Chevy truck of that year the EGR valve is closed at idle with zero vacuum. I used to check them by hooking a finger under and manually cracking it open.If the idle degraded then it's OK or closed and not leaking. Idle doesn;t change then it is leaking or stuck open.

Hey Moonpie, I mean puff puff!:D.....Try turning the air fuel mixture screws, on the carburetor, all the way in and see if the engine responds by wanting to stall out!.....I still suspect the carburetor!

i'm not ruling out the fuel system. i'm mainly waiting for some tools to come in and then i'll systematically check all possible cuprits.

Right! So i'm thinking (hoping) that it might be that flapper door thing on the right side exhaust manifold(i still have the origninal-stock manifolds).

If flapper's stuck, turn it open somehow before you burn all the paint off your intake manifold heat passage. Ask me how I know :D.

Stuck open EGR valve = big vacuum leak. Again, ask me how I know...

From the weather report, sounds like Puff puff is in southern New England..

I'm opting for a burnt plug or possibly burnt plug wires.

How about a bad vacum modulater for the trans or do they not have them on this year truck I dont know when the swicthed. Just a thought.

1) Close, let's just say somewhere in the northeast.

2) i will check the plugs, but the thing is the engine runs ok at 1200rpms and higher without feeling like there is a miss.

3) Yes, these trucks still did have a vacuum modulator for the trans, but i don't think this is the problem(although i'm not completely ruling it out) because i had just changed it 2 yrs ago and there's no white smoke coming out of the tailpipe.

sounds like a pluged idle circuit in carb to me also.:yes:

In regard to that slow shift thing, if you have checked the fluid level, also
check that condition of the hose connected to the modulator valve...If you have a vac gauge, also see if modulator will hold vacuum ... Plus, how does the car do on a cold start-up, like, after sitting over night?

Take a look at the vacuum modulator on the tranny.

I had this exact problem about two weeks ago. Ran fine above 1000rpm, ran rough and stalled below that. Ended up being burnt plug wires.

Jeff

Is the picture of the first EGR the one that was on your engine when it started acting up? It looks like the pintle is completely off of the seat. That would mean the EGR valve is stuck open causing a huge vacuum leak. That could be the cause of your problem. Bolt on the other valve you have or block off the EGR port and see if the problem goes away.

1) Yes, the one on top---the silvery one is the one that is off the actual engine in question.

And then the orangy one is one that is just laying around dormant. And i just took it off for comparison purposes. Mainly because i don't know the difference between positive and negative feedback EGR. Anyways.......


2) The engine starts up, generally, with no problems---overnight and/or in the cold---and it is getting rather cold now.

With the EGR valve off, just block the vacuum side of the port with your finger. if it runs well, the valve is stuck open.
Or you can try to blow into the egr port, you should not be able to blow air through it.
You can also do as suggested above and just substitute the other valve.
I think the valve looks to be open.
You can unscrew the seat on the top valve, and clean it

By the way, the negative valve will have a N atfter the part #. The positive valve will have a P. If there is no letter after the part # it is normal, vacuum will raise the pintle, if the engine is running or not.
Dale

With the egr valve off the engine..you can test the pintle seal with some liquid poured into the exhaust port.The diaphragm test you did does not rule out a weak control spring that will open the valve fully with minimal vacuum and pollute the intake charge resulting in a low signal under the carb at idle speed.That fluctuating vac reading at idle speed can also indicate some intake reversion brought on by a wiped cam lobe on the exhaust side..a bad intake valve seat or broken valve spring or all of the above.

Just a few updates:

1) i took another look under the distributor rotor; The centrifugal advance springs, by my judgment(however limited that may be) they are ok-----they sprung back after i released them by hand.

2) i tried the putting the hand over the airhorn of the carb and it would make the rpm's go down to the point of stalling out. The engine now seem to be able to continue running, but the problem is still basically there as the idle is still very abnormally rough.

3) About the EGR thing: Basically, i did swap valves, but i don't think that was the problem in that upon further examination, i noticed, and this almost slipped by me, is that i noticed that the tube part of both valves is different:

http://i223.photobucket.com/albums/dd31/sencraig/100_0419.jpg

i also noticed that the "pintle" valve thing on both valves ends up being in the same relative position and therefore both valves are actually sealed and ok?

http://i223.photobucket.com/albums/dd31/sencraig/100_0420-1.jpg

Furthermore, i could not blow air thru either one until i depressed the diaphram on both valves. i also ran the engine with out the vaccum hose hooked up to the valve, but plugged the hose. No improvement. Therefore, i don't think EGR is the problem in this case. Incidentally, i don't recommend blowing on these valves directly---perhaps use a rubber hose or something as they taste awful.

Last edited by puff puff (http://www.camaros.net/forums/posthistory.php?p=1123057); Today at 12:12 PM. Reason: grammer

Caught the grammar, but missed the spelling of grammar ;) :beers:

UPDATE:

OK, so i completely changed the distributor to the ESC that was laying dormant in my garage. This one at least looked in better condition than the one i took out.

No improvement and the situation didn't worsen----no change.

So, it looks like it is the fuel system/carb.

Bear in mind that i don't know jack about quadrajets and i am extremely busy this holiday season, so the rebuild/inspection may take a few weeks. Carb probably needs to be rebuilt regardless.

Just another interim update:

Because i'm so busy right now---with the holidays etc., i was thinking of just getting a remanufactured carb and just bolting it on and then eventually rebuilding the carb i have when i get around to it. i fully intend to want to learn to rebuild a quadrajet, but again, the time factor.

The problem is the cheapest reman unit i could find was at jeg's, $300 no core.

So, it looks like i may have to rebuild it now anyways:
1) do you know of any good DVD's that show a step-by-step rebuild in high, almost anal detail?
a) or books or websites? Or even people i could go to?

2) i need to know exactly about the washing part?
a) what chemicals
b) what to put them in
c) any other safety precautions
d) do you even need to wash?

3) i need to know everything about rebuild kits:
a) where to get the highest quality one?
b) basically, everything else you can tell me about it.


Please remember that, not only have i never rebuilt a carb, i don't know anything about carburetors.


4) Do you know of any other places to get a good reman carb cheaper?

HP Books has a Q-jet rebuild book that would be a good start, you should be able to get one from a good parts store. It covers ID, disassembly, cleaning, tuning tricks and reassembly ect. It should be about 20 bucks.....

You can't get more detailed that the exploded diagram that comes with the rebuild kit...

Cliff Ruggles has a book called "How To Rebuild and Modify Rochester Quadrajets" and he also sells the most complete rebuild kits on the planet. EVERYTHING you need. He has every piece you could possibly want to replace. You are definately going to want to get this book. While you are rebuilding the carb, you should make the necessary modifications to it to turn it into a legitimate pavement pounder. If this carb is going on an engine that is ANYTHING OTHER THAN 100% STOCK, you are going to need to modify the idle circuit. The idle tubes are going to need to be removed, inspected for dirt and enlarged. The down channels are going to need restrictors installed sized to the cam as well as the idle tubes. The mixture screw holes will need to be enlarged. The upper and lower main air bleeds are going to need to be sized accordingly and the main jet and rods need to be sized as well. The Q-Jet I had came with a 76 main jet and it was still too lean. The reason being, it had the large .125" main air bleeds. Once I sized them down to .070", I could install a 74 main jet along with a 45 rod and now the incoming air can't overwhelm the fuel. The Q-Jet is an emissions carb so they are lean from the get go. The later the model carb, the leaner they are. If your engine is anything other than stock, the carb has a VERY HARD TIME supplying enough fuel, especially at idle. If you run a larger cam, this is an especially crucial area that HAS to be addressed. Do yourself a favor and DO NOT buy the junk rebuild kits you get from the stores. Call Cliff and he will be more than happy to talk with you about what you have, what you want out of it and exactly what you need. He is a great guy. I buy all my Q-Jet parts from him. Here is his phone number 740-397-2921.

Here's Cliff Ruggles website: http://www.cliffshighperformance.com .....If you don't feel like talking to him on the phone then you can email him, he responds quickly!

Thanks, good link; i was reading their forum and Cliff was saying that one of the biggest enemies of the q-jet along with dirt/debris is "repeated drying out." i think that fits my diagnoisis----i drive the truck for a few days and then it sits for a few days even weeks.

It sounds to me like you got a bad tank of gas. If you have an inline filter in the horizontal position, take it off without tipping it and pour the contents into a glass container. It could also be that the fuel filter is plugging up.

OK, i took the filter out, but there was no gas whatsoever---could it all have evaporated? The last time i started it up was about 2 weeks ago. The filter was rather dirty---i'll get a picture up soon.

Anyways, i think i'm going to start the rebuild. i got the carb off the engine and the carb is not the cleanest in town. However, my questions at this point are:

1) Regarding the accelerator pump lever and the two holes that the linkage rod from the throttle could go into. This is the linkage rod connecting the throttle lever with the accelerator pump lever. i have read that high-perfomance applications---gto, corvette etc. always get the hole closest to the pivot. i would think that the hole farthest away from the pivot would provide more leverage and thus more "squirt?"

2) Does anyone know offhand what size torx bolts that fasten the top to the main body of the carb. And, for that matter what size torx bolts fasten the vaccuum break cannister and idle stop solenoid? Apparently, the more recent quadrajets have these as opposed to regular bolts.

http://i223.photobucket.com/albums/dd31/sencraig/100_0426-1.jpg

Hey puff I can help you with #1... I don't know if you ever played with control line or RC airplanes but they use a bellcrank to move the flaps up and down. There is a fixed amount of of rotational movement in the bell crank and a rod attached to it is then connected to what is called a horn in one of several holes. This horn is mounted on the flap that moves. When the rod is attached to the hole in the horn that is the greater distance from the flap there is less movement of the flap and when the rod is mounted to the horn in a closer position the flap moves more and much quicker...

Apply that to your accl pump arm, when you attach the rod to the hole closer to it's pivot the pump shot is completed faster. Move the rod to the hole further away from the arms pivot and the pump shot is slower.

I would never say one hole is for performance and the other is stock. You use the hole that allows the pump shot to be most effective tuning when tuning your application.

If the fuel filter was empty I now suspect a ruptured diaphragm in the fuel pump. As engine speed increases it pumps fuel faster but at idle there could be enough of a rupture that the pump can't keep up. You will need to check the fuel pressure with a guage to confirm this though.

If the fuel filter was empty I now suspect a ruptured diaphragm in the fuel pump. As engine speed increases it pumps fuel faster but at idle there could be enough of a rupture that the pump can't keep up. You will need to check the fuel pressure with a guage to confirm this though.

Good thought~ this happend on my Dad's vette once. As a test he could throw a see-through filter(Fram G2?) on and see if the pump keeps up when you hold it at low or high rpms.

The torx screws should be t-20 for the 9 outside and t-15 for the 2 under the choke flap. As far as the no fuel, take a look at your fuel filter. Originally they came with a little flap inside the little hole. That was so if the car rolled over, gas wouldn't flow all over the place. Make sure that flap is there and make sure it's facing out toward the fender and not in toward the carb. If it faces inward, it will not allow fuel to flow past it.

As far as the accel pump, it's not so much the hole it's in as it is the length of the accel pump itself. They make shorter accel pumps for high performance. The shorter the accel pump, the higher it sits in the accel pump cavity, thus pushing more fuel when it's depressed. The accel pump has nothing to do with the car starting. It's only purpose is to deliver fuel on high throttle demand to allow the main system to catch up with the extra large amounts of incoming air when you romp on the "GO" pedal. The best thing to do is to remove the airhorn " top of the carb" and clean it out. Make sure there is no dirt on the seat of the needle. It's always best to prime the carb before installing and attempting to start. For high performance purposes, set the float to 1/4" and put the accel pump in the inner hole. If you plan to use this Q-Jet on ANYTHING other than the stock engine it was ORIGINALLY designed for, then you are going to have to make some adjustments to various circuits in the carb. Q-Jets are emissions carbs and the later the carb, the more stringent the restrictions were. They were lean from the get go, especially on the idle circuit and that's where a street car spends 90% of its time. Even at 2500rpm, the idle circuit is still playing a big role in fuel delivery(ask me how I know). I stay in contact with Cliff daily. I have finally got my Q-Jet to the point it needs to be after 6mo. of tuning. It's going to take time. They are probably the most advanced carb ever built. A properly tuned Q-Jet can run like fuel injection(again, ask me how I know), but an improperly tuned Q-Jet can be a nightmare. They are THE BEST carb, PERIOD, for the street, maybe even ever, but you have to make sure it's tuned right. The cam plays a huge role in making the proper settings.

i'm beginning to suspect the pump as well because i got the airhorn off and it doesn't look too dirty in there and the needle+seat look ok--no dirt/debris that i can see. i'm still going to blow some compressed air thru the idle air tubes and clean them out though.

But i was also thinking, let's say it is the pump. And, of course, if i stay above 1200ish rpm, i'm ok. If i'm driving along the highway and suddenly have to take an exit ramp or come to a stop, wouldn't there be enough fuel in the bowl[(hopefully) because i was driving along for many miles at higher than idle rpm] and thus the engine should not run rough at idle if i immediately came to a redlight? (as opposed to just starting the engine up)

If i'm driving along the highway and suddenly have to take an exit ramp or come to a stop, wouldn't there be enough fuel in the bowl[(hopefully) because i was driving along for many miles at higher than idle rpm] and thus the engine should not run rough at idle if i immediately came to a redlight? (as opposed to just starting the engine up)Could be the fuel sloshing from the secondary needle fuel well into the secondaries - bowl fuel level too high - mesure float weight - should be light, very light. Brass floats are seamed and the seam will leak. Phenolic floats absorb fuel.

I would also inspect the float as Everett suggests. If it's old, they do go bad. Get a new float just to be safe. They are not expensive and set it to 1/4"-5/16". The new nitrophyl floats have a line at the opposite end of where they pivot. That is the line you use to set the level. You will need a "T" scale.
http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=68677&group_ID=1120&store=snapon-store&dir=catalog

i'm definitely getting a new float.

But the pump needs to be tested regardless.

1) Given the constraint that i don't want to cut into my stock fuel line, how would you/we install a fuel guage on a stock Q-jet and stock fuel line?

2) If #1 is not possible, then how would we/you/i make up a new temporary fuel line just for testing purposes? i'm thinking to get the appropriate size fittings for the pump outlet side and fuel inlet to the carb. Do you know what sizes these are? Then a rubber hose, then, of course a "T" fitting for the mechanical gauge. Also, would changing the hose diameter from stock--either larger or smaller, affect pressure?

This way, i can take my stock line off, put the temporary line in for testing purposes, then put the stock line back in etc.

By the way, the service manual says that if you have a vapor return line on the carb, the pressure should be 5-7.5 lbs. And, if you don't, 7.5-9 lbs. This suprised me, and i think it's too high, but that's what the service manual says for 83's.

I think you are on the right track as far as fuel pressure testing. The hose size can't have hardly any affect on fuel pressure as liquids can't be compressed.

To install a fuel pressure gauge on a Q-Jet, all you have to do is to drill into the filter housing on the back side and tap it to accept an 1/8"npt fitting.

I run 5psi on my Q-Jet and mine is setup for FULL performance. You need to be more concerned about volume than pressure. It's volume that keeps the fuel bowl full, not pressure. Q-Jets work perfectly fine on 4psi, but I run 5psi just to be safe and I have no problems keeping the bowl full. The stock fuel pump may be getting a bit weak. If so, either replace it with a stock pump or one that supplies more volume. Pressure is not as important.

As far as the accel pump, they either work or they don't. The only real issue these days with accel pumps are the rubber seal. Todays fuels are pretty rough on the seals. Use either a blue or black seal and make sure it has the spring inside it to keep it to the shaft. The accel pump has nothing to do with the engine starting, but it needs to dispense fuel AS SOON as the throttle linkage begins to move. The INSTANT the throttle moves, the accel pump needs to shoot fuel.

1) i discovered that the airhorn bolts as well as the vaccuum break cannister and idle stop solenoid are all T-25, the small screw that secures the secondary metering rods, i had to cheat and use a vise-grip pliers on; i will buy the appropriate bit during re-asembly.

2) Some of the parts are green. Why is this? Are these metal and safe to use carb cleaner on?

http://i223.photobucket.com/albums/dd31/sencraig/65b83eff.jpg

3) i went to best buy for some compressed air cans(Dust Off brand) but discovered that there is some sort of gas in these cans---it's not simply compressed air. Given that carb cleaner is probably violatile, i didn't want to take any chances with this. Any other solutions? Can i just let the carb and parts air-dry? i may be able to borrow a compressor.

I would bet that the canned 'air' will be fine. There are a lot more easily damaged parts in a computer than in a carb. Just don't get into that 'huffing' crap when you are using it.

Anyways, moving on, i discovered, upon closer/better inspection (maybe i didn't have good light) that this carb is a dirty mofo:

http://i223.photobucket.com/albums/dd31/sencraig/f9a6b450.jpg

There was all sorts of crap in there. Even dog/cat or human hair--i have no idea how it got in there. i also gently scraped away a little bit w/ a screwdriver to better illustrate what we are dealing with. It looks like the type of desert with orangish sand---i.e., sahara? The main body is currently being soaked in carb cleaner which is helping big time.

2)The other concern is that after i took the airhorn off, the larger diameter (as opposed to the smaller diameter inner tubes) outer tubes apparently fell off and were just laying in the "auxiliary fuel chambers" as depicted in the next picture. Note that these are not the actual tubes, they are nails used for depiction purposes----i tapped the tubes back into the airhorn---perhaps prematurely as after i installed them, i read that it is recommended to put some loctite on them before reinstalling. i'm not sure if i want to try to take them out for fear of bending or damaging them.

http://i223.photobucket.com/albums/dd31/sencraig/5915896e.jpg

a) what are the "auxiliary fuel chambers" for?

b) what are the tubes for?

The rear chambers supply fuel for the secondaries.
Make sure the idle passages ( the small brass fittings near each of the keyhole shaped main fuel passage) are clear there is an orifice way down in the tube that can clog easily.

Have you gotten Cliff's book yet?

There is also info here: http://www.florida4x4.com/tech/quadrajet/index.php

TTFN
Mat

Normal to see dirt on the floor. Fortunately, the jet height is taller, so no debris into fuel circuit, unless it floats, i.e., animal hair.

1) i discovered that the airhorn bolts as well as the vaccuum break cannister and idle stop solenoid are all T-25, the small screw that secures the secondary metering rods, i had to cheat and use a vise-grip pliers on; i will buy the appropriate bit during re-asembly.

2) Some of the parts are green. Why is this? Are these metal and safe to use carb cleaner on?

http://i223.photobucket.com/albums/dd31/sencraig/65b83eff.jpg

3) i went to best buy for some compressed air cans(Dust Off brand) but discovered that there is some sort of gas in these cans---it's not simply compressed air. Given that carb cleaner is probably violatile, i didn't want to take any chances with this. Any other solutions? Can i just let the carb and parts air-dry? i may be able to borrow a compressor.

The green coating you see is a teflon coating to aid in movement. It helps to prevent binding. There should be quite a bit of that coating on various Q-Jet parts.

As far as blowing the parts off, do you have an air compressor? If so, use that. If not, then air dry them.

On a side note, how are you able to right words and draw lines on the pictures you post? Do you need a special program for that? Sorry about the interjection.

1) Yes, i did get Cliff's book. It's ok.

2) I'm using Photobucket, which is a free service, to host my pictures and it has a built in editor that let's you write, draw lines etc. You could use other free online editors such as vicman's, or if you're fortunate enough, photoshop and then save the finished pic as a file etc. This is something i actually know something about! i can help you with posting pictures and you can help me with carbs!

3) My next concern, although not too much a concern because it deals more with performance and i just want running transportation at this very moment, but since i have the carb abart deals with the secondary flaps.

i have read, in this article actually(3/4 the way down): http://www.73-87.com/7387garage/drivetrain/myqjet.htm

that it says that when the secondary flaps are closed, the tension spring should just be touching the rod off the secondary airflap shaft to just keep them closed. i think they're refering to this as "zero tension." Cliff's book, on the other hand, says to, after the secondary flaps are closed and the spring has made contact with the rod connected to the secondary airflap shaft, that the adjusting spring should be turned an additional 1/2 to 3/4 a turn tighter.

On my carb, when i went to take it off the engine, the secondary air flaps were actually open with no tension on them to make them close---they didn't snap shut; i'm assuming at this point that these air flaps need to be closed most of the time except at WOT, when the secondary throttle plates actually open?
As i further inspected during disassembly, i found that the small hex locknut was loose and the spring was not even making contact with that rod off the secondary airflap shaft even when the flaps were closed by hand.

So, i tried the zero tension thing but the flaps don't snap shut--there seems to be a little binding.

a) What do you think off all this?

b) What size hex is the locknut for the adjusting screw for the spring to set secondary flap tension?

c) How do these airflaps actually work? On air suction/vacuum alone, when the secondary plates are open?

d) Remember that i have a crate 350, which i feel to be a stock engine. In addition, i really just want transportation at this point, not performance. Besides, i weigh 3800-4000 lbs., have a 2.56 gear and really the truck is designed to haul 4X8 sheets of plywood rather than dragging. As a side note, i was able to turn a 16.8 1/4 mile time last summer with this combination.

Find out the reason why the secondary air flap does not close - could be due to no vacuum on choke pull-off and linkage connected through the choke system.

Lock screw is 3/32" allen and a 1/4 inch flatblade screwdriver.

Depending upon application used, real worls results, wind-up of the spring tension may be more than 3/4 turn, could be up to 1 1/2 turns. Too soft, engine bogs when sec's open; too tight, engine never develops power requested.

Secondary air valve opens by the amount/volume of air going through the secondaries; no connections to any throttle or vacuum, other than choke lockout when choke is closed/cold/on.

Interesting. So spring tension on the airflaps is crucial to performance.

1) the service manual says 7/8 ths a turn after making contact. It snaps shut now.

2) Next question, are basically most non-electronic quadrajets 75 and after pretty much using the same float more or less?

Yes.

That's what i thought. The only reason why i was asking (3hrs ago or so) was that my parts store up the street from me said that they didn't have the float in stock, but i decided to go back after the evening shift change and pester them into looking for it again---and "miracuosly" they found it. Although, they still can't find the fuel filter.

The moral of this story and why i originally asked is/are:

1) i believe Carb fuel system parts are being stocked less and less at chain auto stores as compared to 20, 10, and even 5 yrs ago.

2) If it was going to be too much a hassle to order it thru the chains, i was going to order the Edlebrock float (which i now know to be interchangeable with all other after 75 Q-jets) from Jeg's or Summit because they have excellent, fast service. But it looks like, for now, the chains are still an option.

So, anyways, the carb is back together. It wasn't that hard. i really don't know why people fuss over the Q-jet.

For the choke arm, i tilted the carb on it's side and guided the arm in with a paper clip. This way, i was able to match the arm with the choke lever's "dowel" angle. For the power piston, i put a thin screw driver on top of it so it wouldn't pop up while i lowered the airhorn back on. i took the screwdriver out at the last minute.

The most time consuming part (besides getting the new tools, reading, and waiting for the parts to come in) was actually waiting for the carb cleaner to dry. After it dried and the petroleum smell went away, i was able to bring it all inside to assemble. Because it is getting cold here.

So, hopefully this solves the problem. If not, it's probably the pump. i'm running out of things it could possibly be.

Should have been a filter in the kit, either a bronze steel mesh, not the proper name for it, senior moment, or paper one. If not, there hanging next to the oil filters. Most people, including me, removed the filter and ran an external inline, the sinful glass filter, really Pyrex, to see the fuel flow.

Setting the choke for proper operation will be a trial & error method. Once engine starts, the choke pull-off will pull the plate open alittle, its pulling against the thermal bimetal spring, and engine will smooth out to fast idle rpm setting, whatever it might be set, 1400-1600 rpm is ideal.

Next, i need to know exactly what size the inverted flare nut is that screws into the fuel inlet nut:

http://i223.photobucket.com/albums/dd31/sencraig/88d76a75-1.jpg

Not what size wrench to use either; i'm talking about the actual threaded part that screws into the inlet nut. i've already ordered two from jeg's in order to make the new line to install a pressure gauge and they both don't fit----5/16 and 3/8.

It's 3/8 flare. What you have to remember is with flare fittings, it's the flare that does the sealing so the threaded nut is only there to do the drawing together. It's not going to make a tight connection on the threads unless you have the tubing flared to the fuel filter housing. My suggestion on the fuel pressure gauge is to drill a hole in the opposite side where it turns 90*. Tap the hole for 1/8"NPT and run the line from there. The area I am talking about just to the left of that piece of masking tape that has the writing on it on that vacuum hose. Run the fuel feed line just as the factory did and install the pressure gauge on the opposite side.

Maybe i should clarify: What i did was order 2 (one last wk, the next this last wed) NPT to hose fittings---no inverted flares.

Example:http://www.jegs.com/i/JEGS/555/15975/10002/-1

i'm a little (alot) queesy about drilling into the other side of the fuel inlet part. What i'm trying to do is make up a temporary test line with a gauge to test the pump.

The 3/8 fitting appears to have the same thread count as the flare, but it will only screw in very little and then stop.

The fittings that are in that link from Jeg's are PIPE THREAD, not flare thread. Pipe thread and flare thread are differnt. Pipe thread is used for the heater hose connection on the manifold and that port on the back of the carb to attach your vacuum brakes line to. Fuel line and brake lines are flare thread. The picture you have in post #65 is EXACTLY what you need. Pipe thread fittings use the threads themselves to do the sealing. Flare threads use the flare in the tubing to do the sealing. It's the flare on the metal tubing that mates up to the flared center portion on the carb fuel filter housing that does the sealing and makes the fitting and the line tight. The threads are only there to draw the tubing and the fitting together. The correct flare nut wrench size is 5/8" and the correct line size is 3/8". You can go to ANY automotive parts store and buy a piece of 3/8" fuel or brake line(same thing) and it will work.

You have to be careful with those pipe thread fittings. They can actually destroy the filter housing if you tried to tighten them to much. If you look closely at a pipe thread fitting, it actually get wider the farther up the threads you go and that's what does seals on a pipe thread fitting. When the fitting only went it a few threads and then stopped, you didn't try to force it and really screw it in, did you? If you did, then you can crack the filter housing or bung up the threads.

No, i didn't try to force it in. As a matter of fact, someone suggested i try the auto store and get 3/8 brake line with the tube nut fittings already attached----this way all i would have to do is cut it to my needs. i was able to get 24" for $2.50 last night.

Anyhoo, i think i've pinpointed the problem----there is serious flooding going on; The new airhorn-to-main bowl gasket was drenched with gasoline, there were puddles of gas on the intake manifold and there was gas on the flare nut(i didn't tighten it enough). Also, before the carb was rebuilt and this overall problem started happening i subconscienciously noticed these puddles but thought that they were coolant, possibly due to not having enough lighting, also the air cleaner was probably blocking my view. Thus, i didn't consider it a problem.

The reason why i was able to tell now is i know what a new gasket should look like and could tell right off the bat that gas was getting on it whereas the old one was probably pretty drenched to the point where it changed colors. i know that the fuel level in a quadrajet bowl should be at most 3/4 full and definitely not higher than the bowl top.

During the carb rebuild, i put in a new float and checked the level to be good. i also vacuum tested the new needle+seat and put in a new filter. i also checked the old needle+seat, float and those were found to be good and at the right levels.

So, assuming the carb itself is not the problem, what else could cause flooding? Is it possible for a pump to go bad to be putting out too much pressure? The other possibility is there could be trash in the fuel system, but i don't think this is likely as when i rebuilt the carb, it wasn't that bad.

NOTEs:
a) i have a vapor return line on the pump.

b) the service manual says there should be 5-9 lbs. (will provide more detail later, don't have the service manual in front of me---i'm at work) This sounds like too much?

i wasn't able to test the pump pressure last night, will probably be able to get to it tonight.http://forum.73-87chevytrucks.com/smforum/Themes/default/images/icons/modify_inline.gif

Please scratch the previous post---i found the flooding over the intake problem---the inlet nut to carb was not tightened enough. i was able to tell because i got my fuel pressure gauge hooked up and of course in order to see it, i had to start the engine and rush over to the front. And i'm glad i did because it was gushing out.



So anyways, fuel pump pressure good---the service manual called for 5.5-7lbs. and it was within those limits.

No improvement in the situation.

i don't think the carb is flooding at this point, but i'm not ruling it completely out. i guess the next thing to do is to measure the float while the engine is running. i know you need a special tool for that.

i'm leaning towards sticky lifter or valve, but i have my doubts about that as well; Let's say a sticky valve or lifter was causing the engine to run crappy at idle. Wouldn't this also cause the engine to run crappy at higher rpm as well?

i will try to get a video up on how the vacuum gauge is acting, which is very erratically at idle.

Yes. Have you looked into a possible vacuum leak? Also, is this Q-Jet on a COMPLETELY STOCK engine? If not, then what is done to it? If cam, then the carb needs to be modified.

1) pretty sure there's no vacuum leaks, but will not rule out.

2) The engine is the base crate 350 which has been left in it's stock form completely. i'm not sure what cam came with this engine? L82? But at any rate the engine was running fine for 2 yrs and then this problem happened last month.

At this point i must thank everyone profusely for all the help. It seems that interest in this problem has been waning. That's ok. i understand. If anyone wishes to drop out this is completely understandable. i will still soldier on, although probably at a slower pace.

i think what i'm going to do now (besides panic and stay neurotic about the situation)is to anally go back thru everything and do it right starting with the ignition.

Well, actually, before that, i will post a video on how the vacuum gauge is acting.

Refresh our memories. What are the issues you are having?

Do you have an inline filter on it? If yes, put a clear filter on it to verify it is pumping enough gas. One other possible fuel supply problem is a plugged sock on the suction tube inside the tank. Another possible timing problem could be a vacuum advance canister leaking. We haven't given up, we were waiting on the carb rebuild results. Do you know where you could get a known-good Quadrajet to try? I did have a Quadrajet on a 1975 Blazer that started giving me fits. In addition to me installing a kit, two other people put kits in it and it still wouldn't work right. I tried another good Quadrajet and it worked okay. By this time I was quite upset with Quadrajet! Sorry Charlie but I took my Quadrajet, set it on a post, and then I took a rifle and SHOT it! No more problems with that one! I had to give the loaner Quadrajet back so I bought myself a square bore intake and a Holley and never looked back. From my experience, there are good Quadrajets and bad Quadrajets...bad ones get the 'death penalty'!

1) RE: other quadrajets: If, after i go thru everything again, and it still doesn't run right, i may get a new quadrajet. Yes, new rochester built---i think i may know a place that still has them on the shelf. i don't want to give out the info just yet because i'm selfish; It's a matter of equipment snobbery on my part.

2) my test line had the glass filter on it, and yes i'm definitely flowing enough fuel.


3) For 67, very simply at rpms below 800 the engine runs/idles real rough and will stall out. Normally it idles at 600 in neutral and 500 in gear. So we're only talking about 200rpms here. Other than that, there's no other driveability complaints.

So anyways, here is the video:

http://i223.photobucket.com/albums/dd31/sencraig/th_4af873c6.jpg (http://s223.photobucket.com/albums/dd31/sencraig/?action=view&current=4af873c6.flv)

My batteries on the camera ran out, but basically what happens is after the choke opens fully and the carb comes off high idle, it will go to 700, 600, 500 rpm and then stall out. The only way to keep it running after it comes off highstep is to goose the throttle.

So, i thought that i would post that out and see if anyone has had any similar experiences. At this point, i think i am going to go thru everything slowly and methodically starting from the basics---vacuum hoses, ignition etc. i won't post every little detail here unless i get really stumped.

After watching your video and the vacuum gauge I thought you might want to look at this... http://www.secondchancegarage.com/public/186.cfm

Alright, let's say something is wrong with the valve/guides seals or springs. i willing to get in there and fix it but:

1) how likely is it that the engine was running just fine for 2.5 yrs and then all of a sudden one day it starts doing this?
a) the engine is a stock crate 350 installed in 97 by the previous owner and i don't think they put alot of miles on it.

You give it gas with the pedal, vacuum smooths out, meaning its off idle circuit.
One of the idle jets is plugged. Or if rocker noise is happening, a bad lifter(s).
Just my suggestions.

OK, go back a bit. After re-installing the carb and bringing the motor to life.. How did you set the idle? I guess I am asking if you have the idle mixture adjusted correctly? ..Jb

I really wish that you would have used canned air or anything under pressure to blow things out when you rebuilt that carb! Other than idle circuit problems that may have been taken care of during the carb overhaul, I am thinking your film clip just might have given more clues. That vacuum guage is going wild! Did you ever do the compression check or the leakdown test? What kind of oil have you been running, I am guessing it is a flat tappet cam? My thoughts now are leading to a failing lifter or cam. With an increase in RPM you also get an increase in oil pressure that will help a dying lifter. I am really thinking you need to do the compression and leak-down tests but you should remove the valve covers and do a thourough inspection of the springs and even maybe use a dial indicator and check valve lifts (possible lobe failure). Since you have already done the plugs and plug wire tests, I am thinking you just might have some internal failings.

I think the idle may not be set high enough to keep the engine running. Once the carb was rebuilt, did you reset the idle? If so, you have to make sure the fast idle cam was completely off. You also need to make sure the idle mixture screws are set right. Do this, turn the mixture screws in and bottom them out(not hard, just enough to seat them). From there, back each screw out 2 full turns. For the idle speed screw, turn it back until the throttle linkage does not move anymore and then turn the screw in until it contacts the linkage. From there, turn the screw in 3 full turns. That should get you in the ball park and keep you off the main circuit. Start the car and let it warm up. Set the idle to 700rpm to begin. From there, adjust each mixture screw to achieve the highest idle/vacuum reading. After the mixture screws have been set, you may need to go back and set the idle again. If auto, set so that you get about a 200rpm drop. If you get higher than that, you may need to reset the mixture screws. You may also be running to lean. In that case, you may need a jet/rod change or you may need to size the upper and lower air bleeds and then the main jet.

Did you ever mess with the valves? That gauge is going balistic.

Here is what a website on how to read a vacuum gauge said about your exact situation:
Drifts at idle,
stabilizes at higher RPM
Burnt valve; combustion chamber leak.

Look at the valves or the head gasket.

1) The curb idle screw i didn't touch during the rebuild, also i admit that i didn't touch the idle mixture screws during the rebuild either (i guess i should have?), but i swear i took everything else apart except the APT screw. And then i did use the canned air to clean out everything including the idle air passageways after using carb cleaner. The only reason why i didn't mess with the idle mixture screws is because i was worried i wouldn't be able to get them back right. i think now that this was a bad move but at the time, last week or so, i was real nervous. It it's any consolation, when using the canned air i was able to get air thru all of the passageways and they didn't seem restricted.

2) Mobil 1 synthetic 10-30 or 40 (i can't remember the weight exactly)
a)Yes, the engine has the stock non-roller cam.
b)i'll add that this is not nessesarily my daily transportation---it may get driven for a few weeks and then parked for a few weeks. But still..........would this be really that harmful to the cam/lifters?

3) As far as compression and leakdown, i haven't done that yet because i don't have a gauge yet. i will go thru everything the right way up to and including trying a rebuilt carb if nessesary (the carb now will get rebuilt even better/more thouroughly eventually if, in fact, it turns out to be the problem)
Are there any websites or books that can show me exactly how to test/adjust/diagnoise valvetrain problems? i've never done this type of thing before.

I would try Charlie's Post #83 before doing anything else.
Don't be afraid to touch something, keep track of your moves and you can always return close to where you were.

Use the vacuum gauge as a tuning tool. Adjust the mixture screws individually for the highest vacuum reading, adjust curb idle, adjust mixture screws, repeat until no improvement can be made.

The gauge currently is showing you an intake valve is not opening, or an exhaust valve is not opening, more likely an intake. I'm surprised the gauge needle hasn't flown off its axis. And if there is a knocking sound, could be a flat, or going flat, lobe.

Do this before going through all the trouble of setting the mixture and idle. Pull your valve covers and measure ALL the rocker arms in their travel. You are looking for a rocker or rockers that don't travel as far as the others. Provided the valves are adjusted properly, this would indicate a worn cam lobe. If you have a worn lobe, no amount of mixture screw or idle adjusting will help until you replace the cam.

i really hope it's not the cam. Is there any tool to help measure rocker arm travel or is it just visual? i know at the very least i'm supposed to unplug the ignition lead to the distributor and use a remote starter.

Also, if it is the cam, that also means new lifters and pushrods?

Actually, could you tell me everything you know about valvetrain diagnosis/repair or are there any websites/books you know of?

Example: how to measure acceptable valvespring pressure and if no good how to replace.

You can use a remote starter if you want. Remove the plugs to make it easier. What you are looking for is a rocker that does not lift as much as the rest. Measure 1 rocker and then compare that to the rest. There is no set lift because all cams are different. If bad cam, then you are looking at a cam and lifters. No pushrods unless they are bent, but that is unlikely. The only way to test a valve spring is to remove it and take it to a machine shop, unless you have the tool, which I doubt you do. Most people don't. I wouldn't worry about the springs unless if the cam is bad and you opt to install a rather large cam, but if that's the case, then you'll have to change the springs anyway, but if this is a daily driver, you're not going to want to install a large enough cam to require a spring change.

You can use a dial indicator with magnetic base to check valve lift. They are relatively cheap at Harbour Freight. Check the travel of each one which means turning the engine over 16 times. The best you can do to check the springs is visually look for a break in the coil unless you want to pressure up each cylinder with an adapter hose for your air compressor and use a valve spring compressor to remove the keeper from each one. I would just visually check them for now. If the compression test or leakdown test shows the need to have a valve job done, the machine shop will take care of the springs. A cam and lifter swap really isn't all that hard if it does come down to that.

mine was doin the same thing and it was the mass air flow sensor. i unpluged it for a few days and it ran great just the sevice engine light was on. a new one for my car was like $130 i pluged it in and everything was cool. id look at that plus its an easy test.

oh and if yours doesnt have one which im pretty sure a 350 doesnt (sorry i just read the whole thing) i had a jeep that did it too and it was the a throttle position sensor. i think those r just for fuel injection tho. i would look into your airflow anyways... its happened to me several times and thats always what it came back too.

OK, i'm back; Was very busy at work and finally had time to get the engine out of the chassis. i actually had to turn work down the last few days. i suppose i should not complain?

1)The engine is now in a test stand. Primitive but functional.

2)i went to try and find TDC#1 so could i re-install the distributor. In order to do this, i took off both valve covers to see when #6 rockers were moving while #1's rockers weren't and vice versa in relation to when the mark on the harm balancer moved under the 0 setting on the timing tab. i also took all the plugs out to make turning the engine easier and i'll show you the plugs in a sec because i think that may be important also.

What i found was #4's exhaust rocker was loose and not "square" on the "valve stem" as illustrated in the picture. If you pretend that the following picture is a road map, then i could move the pushrod N S E W and really any direction in the 360degree compass, but i could not move it towards or away from myself (up and down) (note: i am putting some words around quotes because i do not know the correct terms to use at this point.)

http://i223.photobucket.com/albums/dd31/sencraig/59f7665b-1.jpg

3) Later, i decided to tighten/adjust this rocker(rotating the crank clockwise about 45 degrees from #1's TDC---#7's rockers moving, #4's rockers not moving etc.) As you probably know, you need to roll the pushrod in between your fingers while tightening down the nut. i immediately knew something was wrong at this point. Voila----we have a bent pushrod.

http://i223.photobucket.com/albums/dd31/sencraig/3a08fb5a.jpg

So........do you think this could be the root of all the problems?

The bigger question would be is what caused the push rod to bend. You may want to check the valve guides. If the head are still on the block you may want to remove to have a look below to see IF there is any damage visa be piston meeting valve. Also check the lifters, note which one come out of which spot, you may have a collapsed one.

Did you use new locknuts when you put those heads together? Some time back we had a lifter ticking and didn't get to it in time. The nut backed off and in the end we ended up with a ruined head, busted piston, and a destroyed block. When I adjust valves, I move the pushrod vertically, up and down, to remove freeplay. I have found that spinning them isn't as accurate.

1) i agree; i have my theories as to why the rod got bent. The more i think about it the more i feel it might have been my fault---at least a 50% chance. There is a good chance i did not adjust/tighten the rocker properly when i replaced the head gasket 2 yrs ago. And after several thousand miles, the problem finally unfurled fully? After all, this is a totally stock engine used only for transportation that NEVER sees more than 3000RPM.

2)No, i didn't use a new locknut; i didn't realize i was supposed to; The locknut seems to have lots of resistance on it---which is normal?

After we lost that engine because of the adjusting nut backing off, I now use new nuts each time a head gets rebuilt or I use a chisel and score the tops of used nuts before installation. I also get to a ticking lifter as soon as possible so that doesn't happen again.

(Unfavorable) Update:

i think i may be somewhat screwed at this point:

What happened was i did run the engine briefly today. It did run roughly briefly. i thought maybe the timing was a little retarded--maybe. i did not continue to run it because the battery was getting run down and i had to go to work.

After returning home, i started to add more water the radiator----i'm assuming that when the engine ran and turned over it took in some water so this is why the level in the radiator went down? How much water should the system hold?
NOTE:Before the engine ran, i filled the radiator with 4 prestone jugs of water/coolant. This fact and my questioning of the system's capacity may be important as we may see below.

i added 2 more jugs of water and during the 3rd jug, suddenly a stream of water started to come out of the dipstick!?!?. Apparently, there is a hole in the dipstick tube and water started to come out of this hole (??????)

These aren't the best pictures but you get the idea?

http://i223.photobucket.com/albums/dd31/sencraig/100_0525.jpg

http://i223.photobucket.com/albums/dd31/sencraig/100_0527.jpg

http://i223.photobucket.com/albums/dd31/sencraig/100_0526.jpg

So, basically, am i essentially screwed at this point? Also, i noticed that the screw on the starter where the brace would go (some engines have this brace, mine doesn't) is rusted thus indicating that this condition may have been going on for a while?

Drain the oil pan and see what comes out - coolant maybe - bad scene if there is water coming out of the drain plug.

I believe about four gallons for a complete system.

I am afraid that you are doomed to a rebuild at least or a new engine at most. The cooling system is not connected to the lube system in any way. If you dump water in the radiator and it comes out the dipstick hole you have major damage inside.

Chapter 5: Houston, we (definitely) have a (big) problem.........

i just thought i would give a quick update:
http://i223.photobucket.com/albums/dd31/sencraig/100_0537.jpg

The reason for the orange is because this is the new Dex-cool extended coolant, not because of rust. After the water drained oil then started to drain out.


Broken exhaust valve, cyl #4---the same one with the bent pushrod.
http://i223.photobucket.com/albums/dd31/sencraig/100_0542.jpg

The valve head, when the cyl head was removed by me, was actually "stuck" to the cyln head.

#4 piston:
http://i223.photobucket.com/albums/dd31/sencraig/100_0546.jpg

Also cyls 2 and 6 were full of oil and probably a mixture of oil and water:
http://i223.photobucket.com/albums/dd31/sencraig/100_0543.jpg

Intake manifold, based on cursory examination seemed ok with no obvious cracks or damage. Right side rockers, nuts, "half-ball-washers"(not sure of the exact term) and pushrods seemed ok.
i will pull the left side head probably tommorrow.

Current plan is to use the 305 i have in my garage as transportation---i know it runs well with no "funky" issues like this "exorcist 350." Then, i will continue to disasemble this 350, completely examine, analize, and hopefully remanufacture the engine.