Author Topic: Idle increase  (Read 909 times)

Offline boat196

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Idle increase
« 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

Offline Kenth

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Re: Idle increase
« Reply #1 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

Offline Cliff Ruggles

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Re: Idle increase
« Reply #2 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......