Questions and Answers
Excessive RPMs
Q. I have a 1979 Corvette. It has a 350 engine, auto trans and 93,000 miles. It has a 4-barrel Rochester quadra-jet carburetor. When I turn the car on the idle is approx 7000 rpm. I don't leave it running very long.The idle screw adjustment is not touching the idle arm. It seems as though something is open in carburetor. That shouldn't be; auto choke, or vacuum line? I have not been able to pin point the problem. If you could give me a few suggestions I would appreciate it very, very much.
A. I think I can tell you with 95% certainty that the problem is in the throttle shaft of the carburetor. This is a common problem The shaft gets stuck or frozen in the carburetor body and it hangs open. You can take the carburetor off the engine and take the throttle plate off. If you can get the shaft out, you may be able to clean it up and put it back together. There's a 50-50 chance this will be a long term repair. And there is no guarantee the shaft will come out. The obvious long term repair is to replace the carburetor.
