I just had my engine rebuilt and now it won't idle. I thought it may need a new carb (had a Holley) now it has a Edelbrock 600cfm and it still is doing the same thing. If i put a rag over the carb it seems to run fine. If i drive it down the road it seems to drive fine. Is this a vacum leak? Could the intake manifold cause this. What should this engine pull on idel for vacum? Getting frustrated.
Engine won't idle
taojaorao
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I just had my engine rebuilt and now it won't idle. I thought it may need a new carb (had a Holley) now it has a Edelbrock 600cfm and it still is doing the same thing. If i put a rag over the carb it seems to run fine. If i drive it down the road it seems to drive fine. Is this a vacum leak? Could the intake manifold cause this. What should this engine pull on idel for vacum? Getting frustrated.
There are a lot of reasons the car may not idle, not knowing anything about what you have tried; have you set the idle speed? I normally keep low idle around 800 and high idle around 1200, works well on my '73; it is also the easiest thing to check.
The car runs well when NOT idling? When you start the car, and press the gas (to bring it above idle) what kind of RPM are you holding it at? Is it running rough at all? Was the carb adjusted?
The car runs well when NOT idling? When you start the car, and press the gas (to bring it above idle) what kind of RPM are you holding it at? Is it running rough at all? Was the carb adjusted?
what type of vacum pressure should there be when engine is running at idle. If you had a mechanic working on this what would you do as far as having them try different things. I already have changed from the Holley Carb to the Edelbrock carb. Thought the Holley carb may be bad.
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8,364 Posts
Depending on the cam, the vacuum should be between 15 and 20 in Hg. Spray around the base of the carb with carb cleaner and see if the motor smooths out or revs up. Could be a vac leak from the carb to intake gasket, but then again the intake gaskets could be leaking too. The vac gauge needle should be somewhat stable at idle too. I had a carb get plugged up only on the drivers side and it wouldn't idle for crap. Do you have a new fuel filter on the car and is it the paper type and not the see-thru plastic filter?
The mechanic did spray around the carb and there was no leaks. At this point i did not ask to see if he had the pcv hooked back up to the carb will ask. The air cleaner is not on the car yet (as far as i know) I had somebody else say that the edelbrock carb might need some adjustment to make it run richer (does anybody know if this could help and if so what do i need to do.
If you cover up the carb and it idles ok you have a vacuum leak. You are sucking air from someplace you just need to find it.Make sure PCV valve is hooked up and the power brakes are if you have them. It may also be an internal leak from an intake not sealed up.
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181 Posts
If it's doing the same thing with two different carbs (I'm assuming the Edelbrock is new). The problem probably lies elsewhere. Do you have power brakes?? Check that line closely if you do (for splits or disconects). Sounds like just an overlooked vacuum connection somewhere. Since nothing cropped up around the carb base and manifold. You say you just had the engine rebuilt so double check the lines for proper reinstall.
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