Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Weird stuttering and high rpms

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Zach:
Carb # - 17057263
Everything is stock, jets, rods, etc, used Cliffs SR Kit at home and base plate rebuilt by him.

First day I was able to take the trans am out since summer and after a rebuild, 40 degrees and sunny out. Car was running great in the garage, good idle, good cold starts, choke works, etc, etc, no issues. I take it out on the road and immediately notice issues, as I am accelerating it stutters really bad and fails to build RPMs, felt as if I was running out of gas. I notice it slowly runs better and better as I am driving around (20+ minutes and a short 1 mile trip (Choke has been open/off for a long time), still not perfect but it is running ok, still noticeable stutter if I accelerate aggressively. After a while and everything gets hot it starts to idle around 1100, not sure what causes this, and when ever I give it gas it takes a significant amount of time for RPMs to drop back down (to 1100 in this case). Not sure what to check would like some insight, thanks.

I suspect it is running too lean but unsure what to change.

73ss:
Does car still have the catalytic convertor? Sounds like a classic symptom of a plugged CAT.

Zach:

--- Quote from: 73ss on April 07, 2023, 05:46:15 AM ---Does car still have the catalytic convertor? Sounds like a classic symptom of a plugged CAT.

--- End quote ---

Cat was removed a long time ago.

Zach:
Going to summarize my main issue a bit fr after fiddling around with it, idle is great and revving in neutral is great, under load coming off idle, part throttle, and WOT, causes a bog/bucking acceleration, it will accelerate and open the secondaries but it is slow and bucks lightly. Adjusted the APT screw from 3.5 turns out - 4, small change I think, 4 - 4.5, no noticeable change.

Kenth:
I would use .073" main jets, 4 turns on APT, secondary rods stamped DA or CE with 1/2 turn preload on airvalves spring.

Also, look for binding weights/springs and broken pick-up coil wire insulation in distributor.

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