|08-26-2012 05:05 PM|
|08-25-2012 11:38 PM|
The original points distributor has been changed out to an electronic distributor, and 2 coils have produced the same results (no change). This was actually one of the first things I did, thinking the same thing, that it was overheating.
The failure is much like when a car runs out of gas, it's not a sudden stall. It will slowly lose rpm's until it cannot run anymore and stalls.
As mentioned, the other issue I believe the car has is possibly a bad torque converter. Is it possible that the converter is loading the engine while in park/neutral? I will be testing the converter pressure here soon. I've seen this type of issue with mid 1980's GM's, where the Lockup Seleniod would go bad, and the converter would stay in a lock-up state causing the car to stall and be hard starting. (not that the T400 has a lockup seleniod, just an idea).
|08-25-2012 09:54 AM|
I tend to get a little lost on these long diagnosis threads so ignore this if it's been covered. Maybe hookup your VOM to the ign power source at the key/switch & moniter what happens when the car dies & won't restart. Could be a momentary failure in the switch ?? Then do the same at the coil , trace all wiring " as it happens" I don't believe you should have fuel dripping out the booster's at idle unless you're way open on idle adjustment. Have you verified that the balancer mark is correct ?? Just some thoughts.
|08-25-2012 08:31 AM|
Important information on GM HEI distributors seen here Technical Reference #5. Hope it helps.
|08-25-2012 08:24 AM|
ck your idle adj'ments again.. the edel carb will be 1 1/2 to 2 turns out. count the turns in see what u got.. also if u put in the points dizzy, just dwell it.. 28-32°. make sure u are using a ballast resisitor with points. u also may have a coil thats ready to die after it heats up...
|08-25-2012 12:34 AM|
We have also tried one of the original dual quads with no change in the way it acts. Choke is not sticking, and electric choke is functioning.
As for timing, I've set it dead on and tried above and below 40 degrees with no help to solving this.
One thing to note, with the Edelbrock carburator, once it gets up to operating temprature, if I push the choke butterfly towards being closed, I can get it to stay running which would lead me to believe it's starving for fuel. I adjusted fuel pressure up and beyond 10psi with no good results.
Also when looking down into the carb it seems that the fuel is dripping out of the boost venturi. I'm not sure if this was the same as with the Carters, but since i still have the same identical issue after multiple carbs, I find that not to be the problem.
I have adjusted fuel pressure via the pressure regulator that is inline, air/fuel mixtures using a vacuum gauge and rpm meter (actually a Fluke Scope), and I'm still at square 1.
The issue is characteristic of Vapor Lock all day long, but I have ruled that out by completely bypassing the existing fuel system with exception of the pump itself. The pump has also been verified for pressure and supply per second.
|08-24-2012 02:04 PM|
Ok I have a couple questions
1 Does it ever die except when stopping at a light.
2 You said sometimes it doesn't restart, what do you do to get it restarted.
3 Have you tried turning the idle up to maybe 750 to see if it doesnt stall (not
the solution just a troubleshooting step).
4 if you put it in gear, hold the brake and stab the gas a little real quick does it
Sounds to me that your idle may be a little low and I am curious if your choke is functioning properly.
People tend to lower the idle on T-Buckets or they are very hard to hold still at a light or stop sign due to the light weight.
I think you may have more than one issue. You have eliminated a few possibilities with some of the suggestions here.
|08-24-2012 10:46 AM|
Chevy 350 T-Bucket, stalling
After driving and the T-Bucket stalls. Have you looked inside the carburetor to see how much fuel is squirting when opening throttle? Check accelerator pump. Can you borrow another carburetor from someone to see if it's the carburetor? What I am saying after you set the initial and mechanical advance you should run about 36* total. When you plug the vacuum hose back to the distributor you should have a reading of 56* total. Also is this vacuum hose connected to manifold vacuum port? If not try that. Another thing when you checked with gas from a can you need to bypass your pump using an electric pump. BTW do you have any fuel filters that might be half plugged?
|08-24-2012 12:18 AM|
It's almost as if the engine is loosing it's ability to pull the fuel in, and of course, as the engine winds down to a stall, vacuum drops off as expected.
Any and all suggestion are welcomed! I'm almost down to the point of tearing the cam out to have a look at the lobes.
|08-23-2012 02:36 PM|
|monster76||To check if its fuel an easy is 5 gallon gas can little 5psi ump and some hose to route them together if it runs good then most likely some rubber hose some where has swelled up giving you pressure with no volume|
|08-23-2012 01:20 PM|
Chevy 350 T-Bucket, stalling
I read in setting timing you set initial at 12* with vacuum line disconnected and plugged. Total of 38* total mechanical and vacuum. After setting initial at 12* idle engine to 3000 set dial of timing light on 36* and check timing again. Should be reading "0" on the scale. The mechanical advance should have a range from 20-25*. If initial is 12+25=37* Now you know how much initial to increase to get 38*. Now unplug vacuum hose and reinstall and that is it. Read this info to understand better than what I told you . http://www.corvette-restoration.com/.../Timing101.pdf
|08-23-2012 08:30 AM|
|cullencombs||Sound like the converter could be some of the issue but not all. Have you done a Vacuum reading on it?|
|08-23-2012 12:07 AM|
The Gas didn't make any difference.
Did a compression test, 148-150psi across the board.
Any other ideas?
|08-01-2012 03:23 PM|
Ok, tried bypassing the ignition switch as recommended above, still the same issue.
Gas tank is almost empty. We are going to put in gas that has no Ethenol content and see if that makes a difference.
We are also going to run a hose from the can to the pump to bypass the existing lines that have always been in the same location. It would be strange that we would get vapor lock now without it ever being an issue in the past. The car was here in Florida for 4 years without issue, then in Georgia for 2 years and now back here in FL. The idling issue only showed up after coming back to Florida.
|07-25-2012 08:18 PM|
still sounds like a fuel issue. you can have fuel pressure but no flow. check routing of fuel line. vapor lock is simply heat creating air bubbles in fuel line. unhook fuel line and you will have flow. buubles will disapate as line cools.
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