Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem

Dripping booster

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Cliff Ruggles:
The float level needs to be at the stock height.  Lowering the float will not cure the problem, and may not have the fuel level high enough in the bowl to keep the accl pump well full.

Might want to back out the mixture screws to at least 3.5-4.5 turns, depending on the size of the holes under them....Cliff

12drag:
I'm having a similar booster problem.
Booster leaks fuel after running the engine.  Engine not running, booster will empty the bowl.
NO change after rebuild.  Replaced "Hygrade"stock rebuild components including float.
Carb seems to be more of a "hot soak" problem; boosters will drip fuel after the car has been turned off hot.  When a restarted is attempted, the booster will continue running fuel into the bowl until empty.  Engine NOT running.
I removed the bowl vent and had the airhorn off several times looking for a problem, without success.
The only thing I could attribute this booster problem to is fuel siphoning through the primary needle and jet.
Any ideas?
1967 carburetor stock 396/350hp.

Cliff Ruggles:
I had one 1967 carburetor in here a few months ago that would flood as long as there was fuel pressure to the bowl, but have never seen a main bowl syphon fuel thru a booster and continue after shutdown and empty the bowl.

The one we had in here had a leak on the pressure side at the bypass plug.....Cliff

12drag:
Cliff, I don't follow the term bypass plug.  Are you referring to the external plug in the fuel filter housing?
Fuel pressure runs 5psi and drops off after engine is off.  Dwell & timing are correct.  Maintains steady 12" vacuum (no leaks) at idle.  I don't believe this condition has anything to do with engine setup.  I went as far as to lower (less fuel in the bowl) the float (8.7grams) until I got a drive-ability problem.  It ran far less fuel over the boosters when engine was off but it still bleed over.  I would appreciate any help with this odd ball problem.
Thank you,
Jim

Cliff Ruggles:
The bypass plug is needed and used on the early 65-66 and some 67 castings.  Those carburetors originally had the plunger type fuel inlet valve, and when rebuilding them the superceded parts are used to convert them to a needle/seat arrangement.   The bypass hole is plugged during this procedure, and a frequent leak point on the pressure side of the system....Cliff

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