Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

OFF idle issue

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Cliff Ruggles:
I like ported vacuum for most set-ups, unless the compression is low and cam too big, and you find yourself needing a lot of timing at idle to make the engine happy......Cliff

Jeffs68:
-UPDATE-

So with the new primary rods and bending the APT spring up a bit, I've eliminated all OFF idle issues. Very smooth transition all the way through, hammer down to about 5200 Revs.

Does seem a little fat at idle, but when I cover the air horn with my hand, no noticeable drop off in Revs.

On a separate note, the repro parts place throttle shafts for the Pontiac set-up are garbage. The primary shaft is fine when the engine is cold, but as soon as you get to operating temp, the shaft is expanding too much and binding up (not returning to idle)

Cliff Ruggles:
I've not been happy with some of those re-pop throttle shafts.  We have had to remove some of the plating from them to get them to fit, and on recently wouldn't fit at all as it had a TON of plating material on it.....Cliff

Jeffs68:
Just received an OEM one from Mr. Pontiac, live an learn I guess.

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