Help..Won't idle when engine warms up.

[gastman]

I just purchased a 78 vette and it will not idle when the engine get warm. Runs fine when cold.
I checked the Choke (works fine) and also replaced the EGR and Smog Pump. The Vacuum lines look like the previous owner had changed the locations....so, I don't know where they are "really" supposed to go (any recommendations on a good Vacuum Diagram???).

Also, Does anyone know if I can take off all the smog stuff on a 78 in California. I believe it is OK if the car is 25 years old or more??

Thanks,
Randy

 

[Yoda]

gastman ~ Welcome to the Corvette Action Center Community ~

Randy,

Does you car seem to run ok, just not idle after the choke has set?

If it runs good just won't idle, then from the front of the carb lower right side is the idle adjustment, all this does is control the idle and does not adjust air or fuel, another thought would be to tak the cover off the aircleaner and see if it idles after the choke sets, you may have the butterfly on the choke closing down.. I have a friend over here near Modesto that is sharp on the old quads. I see him quite often, if all else fails you could make a road trip over the hill and we can take a look at it for you

Now for the bad news.... your 1978 still falls into the "Regulated" smog laws here in CA.. Unless the state changed, the 1974 should fall off the required list this year

Here is a very good site about our Vaccum System

Welcome aboard enjoy the

 

[gastman]

Thanks.... The car runs "OK" even when it is warm. The problem is once it gets down to 1200 RPM's , it cuts off. The Choke is working properly when I remove the cleaner lid it is open and the choke moves the butterfly fine. I did adjust the idle speed screw to keep it running, but then again it is running ~1500 rpm to keep it going.
I think it is a vacuum problem....when it gets warm/hot it seems like it is sucking vacuum from somewhere.
I could not get the picture to come up on the web site you sent...I'll try later.
Thanks again....Still frustrated..R

 

[Stallion]

If CA is like NJ, then you can get historic plates, in which you need not pass emissions, and you can remove whatever you want!

 

[mike weyman]

if the problem is when it is warmed up. it's probably the coil.
another possibility (if it's the original quadrabog)is the governor in the carb, will run cold but stalls out when idiling.mike

 

[mvftw]

Cover the carb with a rag, if the idle goes up, you have a vacuum leak, if it dies you don't have a leak. If you have a leak, use a carb cleaner (Gumout) and spray all over, when the car idles Ok, you found the leak...

 

[Jack]

I recall there have been copyright issues surrounding vacuum diagrams ... Doc Rebuild claiming his diagrams often pirated. DR offers very nice diagrams at reasonably low cost. If you're gonna have a C3 around ... and you're gonna maintain it ... you'll probably need a good diagram. Not an ad nor a plug ... http://www.docrebuild.com/ ... just FYI. If you phone the good doctor's place of business ... have your mind on your order & your order on your mind ... they don't play.
JACK:gap