Engine stops after releasing the gas pedal

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Arend Huisman

Arend Huisman

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Hi there,

we just finished a 318 engine build: 1977 318 block, 1964 crankshaft, heads and intake manifold. We decided to use the hydraulic cam, lifters and rocker arms of the 318.
I runs very fine and if you give it a little throttle it revs up easy. But if you take your foot of the pedal, it dies. With sudden start up it looks if there is no compression on several cylinders. If we let it rest for a while everything is fine...

What could be the problem?
Ideas are more than welcome!

Arend Huisman
 
Ignition timing and or throttle idle screw needs to be turned on to up the idle speed. Do a compression test and see what the psi is.
 
Clean your idle circuit jets with carb cleaner, readjust the idle richness and reset your idle speed up on the linkage stops.

20230123_074625.jpg
 
DO you have a factory service manual? It has all of the tuneup specs so that you can properly tune the car. Until it is in tune, you cannot troubleshoot.
 
Almost sounds like a ECU or pickup is failing with the let it sit scenario. Next time it dies see if you have spark or not.
 
What do you mean with "sudden start ups"

What carburetor is on this build and does it have a choke on it?
 
diymirage said:
What do you mean with "sudden start ups"

What carburetor is on this build and does it have a choke on it?
Click to expand...
I mean when i start the engine immedietly after it dies. If i wait 2 minutes it's oke. It has the original carburetor with choke.
 
Arend Huisman said:
I mean when i start the engine immedietly after it dies. If i wait 2 minutes it's oke. It has the original carburetor with choke.
Click to expand...
original to what?

the car it is in, the 318 block or the 273 intake?


ok, so you've been given a few different things to check out first
did you clean the idle circuits and and what are you using to set your idle speed...the screw or the throttle cable?

what kind of transmission does it have?
and if it has an automatic, what is your idle RPM in neutral, park and drive?

any chance you did a compression test while building it?
i guessing this is a ground up build, no?
 
Thanks for al the replies! We use the carburetor of the 273 and we cleaned and adjusted it right. There is no vacuum leak, checked that too. We will have to check the compression before and directly after it dies.
We have the impression it has something to do with the hydraulic valves that stay pumped up for whatever reason.
 
With hydraulic valves, do you mean the lifters?

(Die kleine metalen buisjes tussen de nokkenas en de stoterstang)

Het zou in principe kunnen dat die door vuil iets te hoog opgepompt worden en een klep open laten hangen, maar die kans is wel heel klein
Bevondien, op het moment dat de desbetreffende zuiger zijn bovenste dode punt bereikt is het einde oefening voor die klep

I would suspect a wiring issue, or a mechanical issue on the adjustment of the carb or choke
 
We changed the valve system back to adjustable lifters, problem solved!
Thanks to anybody who reacted. :thumbsup:
 
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