General Category > Quadrajet Carb Talk and Tips

67 GTO 7027262 Fast Idle

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rickmpontiac:
I removed the carburetor and checked the throttle plates for binding and closing completely. I used 1/4 inch strips of paper to check for consistency around all four plates while closed. I  tried different timings w/o vacuum advance between 6 and 18 degrees at idle. I can get the idle RPM down to about 800 w/o vacuum advance. Connecting vacuum to the advance from either the ported or manifold brings the RPMs up to 1150 to 1200. All of this while at operating temperature and choke fast idle not a factor.  I could adjust the idle speed down to where the car would die with the Edelbrock #1407 that I removed to restore the originality of the car. It does have a 67 cast iron manifold with the the heat crossover. I currently have the stainless steel plate sandwiched between two correct gaskets for the manifold. I added the top one trying to make sure there was no vacuum leak between the carburetor and base plate.

Kenth:
7027262 do not have a ported/timed source for the vacuum advance, it is manifold vacuum in that port.
Leaking hot idle compensator at rear of float bowl?
Flange gaskets/plate installed upside down?

rickmpontiac:
The Pontiac Service manual says vacuum advance should run off manifold vacuum so looks like I'm good to connect it either place. I've verified the gasket and stainless steel plate are installed correctly. I do have a gasket between the stainless steel plate and the carburetor in addition to the one between the plate and the manifold. I'm not familiar with the hot idle compensator so may check into that.

Cliff Ruggles:
Pontiac Q-jets in 1967 will use HIC.  I'd block the hole under the HIC as the HIC valves are known for leaking and causing high idle issues.  It really isn't needed anyhow....

rickmpontiac:
Thanks Cliff, I will take a look at it. Appreciate everyone who provided suggestions.

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