Thread: chevy 350 high idle

Tweet

hi i have a chevy 350 in my 72 chevelle engine has been overhauled but the idle is too high like around 2000 to 3000. it has a 600 cfm edelbrock carb but when i adjust the idle screw down the engine shuts off. cant get to idle correctly.

Check for a vacumn leak.

were exactly would the most common vaccum leak be

in one of the vacume lines connected to the carb,power brake booster or your distrbutor! retorque all of your carb & intake bolts,

Originally Posted by 66black289

hi i have a chevy 350 in my 72 chevelle engine has been overhauled but the idle is too high like around 2000 to 3000. it has a 600 cfm edelbrock carb but when i adjust the idle screw down the engine shuts off. cant get to idle correctly.

First look for any hoses that are off and then spray the old "break clean" around the carb.
If the rpm's go up you found the leak.
It sounds to me like you might have a timing issue also.

Originally Posted by erik erikson

It sounds to me like you might have a timing issue also.

Man, you have good hearing!!

Actually speaking of a timing issue, my wife seems to think I have one of those as well.

Originally Posted by TyphoonZR

Man, you have good hearing!!

Actually speaking of a timing issue, my wife seems to think I have one of those as well.

If you press your ear really close to the screen you can hear it too.
See what I mean.

I can hear it all the way to michigan-----oh wait-thats my cat! Also make sure your eldejunk butterflys arent stuck open a little on the gasket or intake.

i checked the vacuum lines and they seem fine the intake doesn't leak either. i played with the timing and it seemed to stay at idle for a couple of seconds and then it dies, before it dies i give it some throttle and the rpm jumps back high. could it be the carburetor i am not so sure.

I had an old holley pull this one on me, make suer that the throttle return spring is strong enough to return the linkage to closed position. Disconnect the spring and manually push the arm forwards, also at the same time wiggle it up and down to make sure the shaft bushings arent worn and sucking in air. Good Luck keep us posted

i found some remedy to the engine when the car is idling @ high rpm i put my hand over the carburetor and the engine goes to low idle but kinda rough then i move my hand away and rpm increases

I would be suspecting a vacuum leak inside the motor if you can't find it by spraying a combustible material around the outside of the manifold. The intake face where it mates to the head could be a different angle, being gapped open on the inner side of the intake. The motor would thus be sucking non-combustible crankcase vapors into the ports. The same thing could happen even if the intake/head surfaces are perfectly parallel (not likely) if one or both of the intake gaskets are mis-aligned and not forming a perfect seal to the inside of the motor.