1974 Corvette high idle long time to come down.

[Don I.]

Hi Guy's! My parents own a 1974 Corvette, 350 CID with 4 speed. When they start the car cold it takes so long to get it to kick down to idle. Even after the car is warm and the temp a little over 110 it's still running at around 1500 RPM's. Then after one hard slap at the throttle it finally comes down to 700 RPM. Any ideas? Anything to replace or repair? Carb is original to the car. Could it be the little metal coil on the intake manifold that needs replacing? Thanks in advance. Don

[Gene M.]

Re: 1974 Corvette high idle long time to come down.

Don,
Check choke adjustment, sounds a bit rich. The linkage could be sticking a bit. Try a little carb spray on links followed by some wd40.

[Stuart F.]

Re: 1974 Corvette high idle long time to come down.

Besides what Gene mentioned above, I'd be looking at the choke pull off diaphragm. Check it with a mty-vac, if you have access to one, and also check the linkage and hose.

Stu Fox

[Don H.]

Re: 1974 Corvette high idle long time to come down.

It is not designed to drop down on it's own. You have to give the throttle a kick to drop it down to normal idle, just like you did.
Nothing is amiss.

[Don I.]

Re: 1974 Corvette high idle long time to come down.

We understand that you have to kick it down manually but it won't come down. My father keeps slapping the throttle but still hangs around 1500 RPM. The last time we started it it was in the 80's here and the same thing happened. The weather was warm and the car didn't need that much choke at all. I did notice looking at the choke was that the choke plate was pretty tight. A lot of force on it to keep it closed.