Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

79' - possible vacuum leak

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Cliff Ruggles:
"Port vacuum to the vacuum advance moved from manifold per the dizzy rebuilder."

+2 on Kenth's comments, moving the vacuum source to the distributor was not a good move there.  That engine makes PLENTY of vacuum at idle with 18 degrees initial timing.  It doesn't need the timing clear off the scale at idle speed.  This requires closing down the throttle angle even more and as you found out the exhaust can get pretty stinky.

Did the shop that "rebuilt" the carburetor install bronze bushings in the throttle shaft?  They are too loose from the factory for my liking and not uncommon to see them sucking some air around the primary throttle shaft if nothing is done to tighten things up there.....

jvmagic:

--- Quote from: Cliff Ruggles on February 05, 2022, 04:02:06 AM ---"Port vacuum to the vacuum advance moved from manifold per the dizzy rebuilder."

+2 on Kenth's comments, moving the vacuum source to the distributor was not a good move there.  That engine makes PLENTY of vacuum at idle with 18 degrees initial timing.  It doesn't need the timing clear off the scale at idle speed.  This requires closing down the throttle angle even more and as you found out the exhaust can get pretty stinky.

Did the shop that "rebuilt" the carburetor install bronze bushings in the throttle shaft?  They are too loose from the factory for my liking and not uncommon to see them sucking some air around the primary throttle shaft if nothing is done to tighten things up there.....

--- End quote ---

Thanks for your response, I appreciate it.

So I assume it’s best if I put it back in manifold vacuum?

If the shop did not install the bronze bushings in the throttle shaft, what can I do myself? Is it a simple process or should I take it to the shop? Is there a way to confirm that this may be the culprit?

tayto:
grab the bellcrank and see if there is play. i usually crack the throttle open and then do this.

jvmagic:

--- Quote from: tayto on February 05, 2022, 10:09:46 AM ---grab the bellcrank and see if there is play. i usually crack the throttle open and then do this.

--- End quote ---

Is the attached photo what you are referring to?  Can I do this with the engine cold?
If this bell crank is loose or has play how does this cause hissing/vacuum leak. Sorry for the ignorance.

jvmagic:
Q-jet bell crank ?

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