Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Q-Jet 17057274 idles too fast

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429bbf:
bt. im having a brain cramp im still thinking about your first post. (when i open the sec.flaps it slow down.) i think one of two things . is it possible that the lower sec flaps are open a little bit and the upper are closed and the vacum is pulling fuel out the sec. tubes causing the engine to idle fast?try this take the sec.needles off the hanger and leave them down in the holes. fire up the engine and open up the top flaps and see what happens. also on the primaries .(that carb should have a front apt)screw it all the way down and take a straw or something small and push the needles all the way down with the engine running.one last thing not to be a smart (a) if this has had this problem does it have all the matching parts (airhorn -fuelbowl-baseplate. )and if so what about the right gaskets.let us know what you find. dean

beertracker:
Cliff called it!  :)  Problem solved.   The secondary throttle plates were slightly open at idle letting air directly in the intake manifold.   I solved the problem by bending the secondary throttle shaft spring so it exerts more force at closure.  I just tested this out and the engine idles at 720 rpm.  Much better than the 1400 rpm idle before.

I discovered the partially  open secondary throttle plate the last time I removed the carb.   Strange I didn't see this previously when I removed the carb.

Thanks to all who contributed,

bt  :)

Cliff Ruggles:
The throttle plates should be fully seated at idle.  Make sure there is some play in the linkage that applies them, or they will not fully seat each time they close.....Cliff

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