Okay. So I purchased a 74 Stingray very recently. The ex owner told that there was a vacuum leak he had not located yet and we adjusted the idle very high for the drive home to be sure she wouldnt stall. When I got her home I adjusted the idle to a normal speed and well the Vette basically stalls in idle once warmed up but will never stall while driving and never stall in park.
I took her to my mechanic in my hometown. This guy has a great reputation for working on old muscle cars and he did good work on my two previous Vettes. So he tells me the carb is the wrong carb and does not fit well with my intake. The carb is a street avenger and the intake, an edelbrock performer 2101. There suppost to fit right? He says it would need a spacer to fit but it wouldnt clear my hood so I have to change the carb. I trust him and give him the ok for the job. He puts a holley 650 cfm ''Corvette replacement'' carb on.
Take her home and I basically get the same symptoms. Seems to work fine when just started but when she warms up she will stall at idle if I stop at a light for too long. Once she gets really warmed up she even stalls at stop signs! So I take her back to my mechanic who tries different things and sends me for road tests after. He checked the timing witch was ok, he readjusted the carb a few times and in the end disconnected and plugged the vacuum hose from the carb to the distributor and set the timing in consequence. She seemed less worse and he said the only thing else to do would be to change the carb powervalve because the carb needs a powervalve that will compensate for the cam I have. The ex owner however was strongly suggesting an intake gasket problem.....

Drove her on the weekend and she didnt stall. Thought my problem was solved. Tried her again this morning and all was fine and I set the idle to 700rpm as per indicated in the haynes manual. Well I decided this afternoon to drive her on the highway for a long test drive. As soon as I got off the highway, she died. Restarted her but as soon as I take my foot of the gaz she stalls! I had to drive with both my feet to get home as taking my foot of the gaz would cause her to immediately stall even if the car was driving at a decent speed! So I went from an idle problem to a big stalling problem and barely made it home!
Internet research suggested an intake gasket leak getting worse so I decided to take the intake off. I have it off now.

Here are some pics for a question I have:




There are some white stains on the heads around the coolant passage holes.I cant seem to clean all the stains off with thinner. Was thinking of getting some brake cleaner and trying it tommorow. Does it manner if I cant get all the stains off? I know the surfaces are supposed to be perfectly clean but if its smooth but with a few stains like that is it ok?

Also, Ive read that I should not use the gaskets for the front and rear ends between the block and intake and instead use black silicone. What do you guys think? And for the intake gaksets, do I just slap em on or should I put some silicone or gasket maker underneath?

Secondly, what do you guys think of this problem? Does it sound like a vacuum leak? Or could it be something else?

P.S: for technical details, the igniton was changed to electronic, spark plugs and wires are all relitively new, cap and rotor recent...timing is apparently ok....Cam details: Comp Cam XS256S cam & lifter (218/224 , 0.465/0.477)...Heads: EDL-60909 heads, 64cc....for the rest she is pretty much matching numbers...

So Im thinking of just resealing the intake and changing the powervalve on my carb but I would really appreciate some advice and opinions here on what could be wrong and if Im on the right path here!

Thanks

 

Anybody?

 

Well, you're stalling problem wasn't the carb, was it? The first thing I would do is take the new carb back to your 'genius' mechanic and tell him to refund your money and your old carb. Next, if you are going to leave the heads on your engine, cut some pieces of duct tape to cover the intake ports so that you can work on the rest of it (you don't need to get cr@p in the valves/cylinders). Then use a clean rag with some vinegar on it to lay on the "white stuff"; that's just mineral deposits from the circulating water in the block. Volatile cleaners won't remove it, but vinegar will. Since your engine runs fine with some throttle applied, you either have an air leak into the intake manifold or the idle "system" on your engine is not set up correctly. I suspect the air leak because putting on a different carb didn't really do anything (from you description). When you reassemble the intake/carb, use a Fel-Pro [blue] intake gasket kit; the end seals will be neoprene rubber [or Viton] and should work just fine...but you can do a "dry run" test with the two 'bare' intake-to-head gaskets by placing only those on the heads (no end seals) and setting the intake in place. Then measure the gaps on the ends to be sure the end seals that you have will completely fill those gaps when you install it for good. Why do this? Because your engine could have been rebuilt/machined in the past and a lightly decked block will change the end gaps...so that they might not seal with stock gaskets. If, in fact, those end gaps are too large, you will have to buy or make some gaskets out of thicker material. PM me, if you need to, for details. One more possibility....if your car has power brakes, you could have a failing diaphragm in the brake servo which might just be the vacuum leak causing your problem. To test for this, just disconnect the vacuum fitting going to the P/B servo and cap/plug the carb connection. Then start it up to see if it idles or not.
Steps to do:
1) dry fit intake & intake [side] gaskets to block and measure end gaps,
2) use new end gaskets or buy/make new ones to fit properly,
3) install gaskets (no sealant on intake-to-head gaskets; sealant on corners of end gaskets); install intake & carb,
4) fire it up to see if you fixed the problem,
5) if "no joy", disconnect & cap the P/B servo [assuming you have one] and try it again.
At least, nothing in the above write-up will cost you any additional money....and if you follow the first bit of advice, it will save you plenty. Good luck.

 

I really doubt you have a power valve problem since the car has has similar problems with 2 different carbs.
When you get it back together again and start adjusting the carb, timing, etc, you really shouldnt be getting
your details from the Haynes manual. Everything in there is based on a stock engine.
If you havent read the timing sticky yet, go read that.

 

Thanks for the reply. I will follow your advice and try vinegar. And like you say once Ive reassembled if the problem is not solved I will disconnect the P/B. I have the intake gaskets but no end seals...found the 2 intake gaskets lying around in my garage but with no end seals. Ill have to make the seals with silicone or gasket maker...

Ill post an update once Ive got her runnin again.

 

Thanks for the reply. Yes I quickly read the sticky. I will read again when reassembling. Also....I kinda forgot to flush the coolant before taking of the intake but I seem to be able to do the job without the coolant being flushed!

 

Spend a few bucks and buy the Fel-Pro intake set (unless yours is already). Small price to pay for piece-of-mind that it will seal and stay sealed. Don't use any sealant on the head/intake gaskets.

 

Thanks again for the advice.

My set is a fel pro. Its an old story from the 79 Vette I use to have. A GM dealership had diagnosted an oil leak as a head gasket leak on a brand new 350 crate engine I had put in it. The guy who sold me the engine gave me a head set. Turns out the leak was a plastic plug that came out of the block and the guy let me keep the headset! I had forgot about it but foud it yesterday in my garage so Ill use the intake gaskets from the set.
Experiences like these and the timing sticky have convinced me to try and do as much repairs as I can myself!
Going to buy a Timing light and vacuum gauge tonight!

 

Don't forget the tach/dwell meter...if you still have a points ignition system.

 

Not a points system anymore!

 

Well I replaced the Intake gasket and during the replacement I gave the carb to my mechanic who changed the powervalve. Took her for a roadtest tonight and she only stalled once I got home after a 20-30 minute drive. Witch is pretty good considering she used to stall right away with the lights up. So she stalled once I got home but I restarted her and put her in drive and I couldnt get her to stall again....

Now I havnt set the timing or properly adjusted the carb so I will be doing that tomorrow. So the problem is either solved or almost solved! I will set the timing at 36 tomorrow and adjust the carb and then take her for a long long drive.

Question: Right now the vacuum advance is still disconnected (my mechanic cut the hose and plugged it). He says to set the timing without vacuum advance...What do you guys think? Do I need vacuum advance?

Thanks

By the way, felt good doing the job myself! Saved money and was a good learning experience.

 

Yes. You need the vacuum advance...assuming that it is working correctly. Leave it plugged off when you set your engine's initial timing; then re-connect the line to the dist. advance can and use the timing light to observe what the timing mark on your balancer is 'doing'. With the advance connected, the timing mark should have moved 'ahead' of it's initial setting...the mark should be somewhere around the 12-o'clock position on the harmonic damper. While watching the 'action' of the timing mark [timing light ON], give the carb some throttle and it should advance even more (from the mechanical advance system in the distributor). If that appears to be working properly, button it up and enjoy. {Note: If, when you set timing and attach the vacuum line to the dist. can, the timing hasn't changed, your advance can is bad and needs to be replaced.}

 

Well I need new answers!

I set the timing and adjusted the carb tonight. Well same problem. She wont stall in park. In drive with my foot on the brake, she doesnt seem to stall untill I put up the headlights. Tried different timing, different adjustments but the problem is still there no matter what once I put up the headlights. With the headlights up she almost immediately stalls! Now if I were to keep her in drive with my foot on the brake without the headlights on she would probalby end up stalling after a few minutes when she is really hot as she was before I changed the intake. And like before, popping up the headlights makes her stall almost immediately!

So know its probably not a timing issue, not a leaky intake gasket either. My mechanic changed the powervalve to compensate for my cam also. So what else could this be????

Could this be an ignition problem or a fuel pump issue?

Quick resume of my problem: -when hot and after a long enough drive, she will stall in drive if im stopped at a long red light. In the same circumstances(hot and after long drive), popping up the headlights makes her stall almost immediately if Im stopped at a light or a stop.
Never stalls while driving or in park, only when stopped in drive or reverse....Except for that she seems to drive fine!

All advice is appreciated!

 

If turning on the headlights is making it stall, it is likely a vacuum leak.
Remove the vacuum hose that operates the headlight doors and plug the port.
If the stalling stops you can go looking for leaky actuators, seals, relays, etc.

 

Thanks for the reply. That makes sense. The hose that actuates the doors is at the front right? I know there are 2 vacuum hoses that seem to be going to the headlights. Anyways Ive seen the headlights vacuum diagram so Ill try removing hoses and plugging ports untill I find the problem!

 

Update

My Vette will stall at idle when I stop at a light and am therefore in drive with my foot on the brake. If I pop up the headlights, she stalls almost immediately,with headlights off she ends up struggling and stalling but it takes much longer.....Also, the problem is truly there when the Vette is warmed up pretty well. At cold, she doesnt seem to stall. Ive all ready replaced the intake gasket. I disconected the vacuum at from the hose coming out of the base of the carb and intake. I actually dropped my gauge! It still works but doesnt go under 10! So my readings might actually be reality+10. Now, by putting my gauge where I put it, there was no vacuum going to the headlight or braking system so I can rule out an leaky hose, check valve or anything in those systems! The gauge read 23 and seemed decently steady. The needle was moving but the rpm is also varying slightly so the vacuum gauge varies slightly but stays pretty much around 23. Giving her gas doesnt make the reading go up with is a good sign if Im not mistaking...Now here is the weird part, if I pull the headlights up with vacuum disconnected, they of course dont pop up but the Vette stalls almost immediately! The lights are of course drawing current when turned on. So Im now wondering if this is an electrical issue? Could the alternator be producing insufficent current and turning on the headlights is too much for it to handle?
Another thing to note is I have a current draw for sure as the battery dies if I dont start her up for 1-2 days. I changed the battery and if I disconnect the battery, she fires right up after a couple days so there is defenetly a current draw. Could the draw be strong enough to cause a stall when in idle and the headlights on with my foot on the brake?

If any of you are thinking timing, I set the timing at 36. My mechanic cut off the vacuum advance and said to set it without vacuum advance. I reconnected the vacuum davance tonight and it didnt solve the problem...

So I would really appreciate some advice and opinions here. Sorry for all the details but I think they are important...

Chris

 

Anybody?

 

Jeeze, this sounds exactly like my problem I am having. Maybe I could shed some light on this even though my problem is still around.

First off, you gotta check your gas tank for debris. If you have alot of rust or garbage in there, it can clog your fuel 'sock'. To get the fuel 'sock' out of there you just need to take both lines to the fuel pump leading from the tank and get a air compressor and blow out the sock. It WILL NOT hurt your fuel tank floatin around till you drop the tank some day.

Two, you have a faulty fuel pump. Just replace it.

Third, Have you ever tried replacing your fuel filter(s)? Since my tank is dirty, I go through a fuel filter every 2-3 weeks. I just dont have enough money to buy a new tank and fuel lines.

I still have the problem of stalling. It will start every time when its cold buy when I turn it off after a drive and turn her back on, she tries to stall after 5-10 sec. Plus if she does run, I'll hit the gas to speed up and she'll choke once in a while. So I dont drive her very often.

I hope this can bring some insight to your problem. We are all in this together.

 

Kyle, have you fixed your problem?

I seem to be having the exact same issue. I've bumped my idle up to 1K, but when I put it into gear (and stopped), is starts to bump bump around 500-800, but then shortly stalls.

Anyone have a clue? Is this a fuel issue - should I replace the fuel pump?

Thanks,
Matt

 

i might have missed it in the posts but did you try to run the car with all the accessories blocked off.

block off the vacuum lines from the manifold that control the headlights.

then try it again.