Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Idle increase
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boat196:
1970 Corvette (7040207) it recently started to increases idle speed from 800 rpm to 900 rpm. After the motor comes up to operating temperature. I notice this while I’m out driving, and when I come to a stop. I’ll tap the throttle with no change in higher idle speed.
Bob
Kenth:
Check for misaligned / jerky fast idle cam, idle-turn screw or choke pull-off.
Check the function and adjustments of all possible solenoids on the carburetor.
Check the function of the choke / bimetal and that the flange gasket is correctly mounted or broken.
Also check for broken / detached vacuum hoses at the carburettor and leaking / broken valves and devices at the other end of the vacuum hoses from the carburetor / intake.
HTH
Cliff Ruggles:
If you don't find the issue there check the timing. The mechanical advance part of the distributor may be allowing a little timing in at idle speed causing the increase. I see this a LOT with vehicles brought in here to custom tuning having similar issues......
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