75 Corvette High Idle 7045222

[Inca32]

1975 Corvette idles about 1100 RPM with idle screw backed all the way off. I have done all the checks for vacuum leaks at headlights, heater/AC, transmission modulator, choke, EFF valve, EGR blocked off. Tested intake manifold and carburetor with propane and found no leaks. Choke is correctly adjusted and works as should. Checked new gaskets for correct fit, adjusted float to spec, new fuel filter, valve/seat, accelerator pump.
Set initial timing to 6 degree @ 900 RPM (can

[Cliff Ruggles]

I would check the throttle plates in the baseplate to make sure they are closing all the way and sealing up in the bores as they should.

It has to be getting air from someplace to idle that fast since the timing is only at 6 degrees BTDC.....Cliff

[Frank400]

Just saying because I once had the same problem and overlooked the fact that even though the idle speed screw was backed off all the way, the throttle was resting on the fast idle cam.