Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Cadillac 500 unable to idle

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tschmitt:
No, electric choke that I disable when on the test stand so choke is open.

tschmitt:
The incredibly low manifold vacuum is definitely a issue that I'm not sure extra bypass air will resolve. Checked compression on all cylinders and they are all 150# or above. May need to take the intake back off and put on another set of gaskets reseat. Gotta be a major leak somewhere unless the cam is wrong.

Cliff Ruggles:
Agreed.  At 2000rpms that engine combo should be easily making over 20" of vacuum.  10" would be really low at 1000rpms assuming you had adequate timing in it.

At this point I would check for a huge vacuum leak someplace, or ignition timing WAY off the mark. 

Hopefully it's something easy and something worse like the camshaft out of phase, etc....

tschmitt:
Pulled the intake off and applied a new gasket. Intake gasket did have one area that looked like it may have been leaking internally. Also tore the carb down again to make sure everything was in place, rechecked the base plate to main casting surface and indexed the throttle blades again. Rechecked the fuel inlet set with a vacuum and it failed this time. Reseated it 10+ times with a check ball and it finally held. Will let the new intake gasket and RTV sit 24 hours and then fire it up again tomorrow. Fingers crossed.

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