Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: boat196 on January 06, 2022, 05:20:29 PM

Title: Idle increase
Post by: boat196 on January 06, 2022, 05:20:29 PM

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

Title: Re: Idle increase
Post by: Kenth on January 07, 2022, 01:29:13 AM

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

Title: Re: Idle increase
Post by: Cliff Ruggles on January 07, 2022, 05:00:05 PM

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......