The carter afb on my 64 conv drips gas from the accelerator pump nozzles after car is shut off. Seems to do this when motor is hot and when cool. Checked heat riser and it is open,Also blocked off riser ports on manifold. Could it be a leaking needle and seat! Floats are set right as far as i can tell.Any ideas would be appreaciated.

 

If it only leaks from the nozzles and the float level is OK then it could be the check ball or needle under the nozzles.

 

What should i look for on the needle or check ball assy ?

 

At the risk of being redundant - does this mean you pulled the top off of the carb and actually measured the float level? Another slightly more remote possibility is maybe one is leaking.

I think Plaidside means the needle and seat. If some dirt or trash is keeping it from seating (closing) fully it will continue to allow fuel in above the float setting when the engine is running. They can be examined at the same time the float level is checked.

 

Stingray 371,

You mention that the fuel dribbles into the engine when hot or cold. If so, then your floats are out of adjustment as no fuel pressure is being generated when the engine is off.

I'm guessing that your problem appears to be a typical engine shutdown problem caused by "hot soak". This is the time after an engine is run when there is no more air flow through the compartment and heat from the block builds causing the fuel to boil in the carburetor. Several things can cause the fuel discharge into the pump squirter passageways. One is improperly adjusted floats that allows the fuel bowls in the carb to fill up too high allowing the boiling fuel to overflow into the engine. The floats on a Carter AFB are set by turning the airhorn upside down and adjusting the needle seat tang so that the top of the floats are parallel to the airhorn with the gasket in place. This is not the measurement method, but it is generally a good place to start. Another cause of fuel bleed is a leaking float that allows too much fuel in the bowls while the engine is running. When the engine is shut down, the over-filled bowls allow fuel to boil over into the engine. The third cause is a lack of a thermal barrier between the carb and the intake manifold. A 1/4-inch phenolic gasket and/or a stamped sheetmetal heat diverting plate between the carb and manifold is needed to keep the carburetor from absorbing too much heat. Finally, your engine timing may be too retarded causing the engine to run hotter than normal and raising the engine compartment temps to a point where the carb and fuel are affected. I hope this helps. Good Luck.

 

Pulled carb off car today and removed top. Checked float adjustement and it was 7/32 .Float drop was 3/4. also checked floats for gas inside floats.Checkedneedle and seat valves and they looked good.Ran car to normal operating temp then shut off.Carb body was cool but i still had fuel dripping out of acc pump nozzles.I loosened fuel line to carb and it had some pressure on it,Guess this is normal.The only thing i can think of is try new needle and seat valves.I have a stock AC fuel pump but have not checked pressure.Any ideas would be appreciated.Thanks for taking the time to reply,

 

Check pump lever/linkage dimensions against shop manual specs.

Duke

 

stinray371 stated "drips gas from the accelerator pump nozzles after car is shut off."
He did not mention fuel from the boost venturis.
If you take off the pump squirter nozzle and turn the carb upside down there should be a small brass needle or check ball under the nozzle. If someone removed it or forgot to put it in this could be his problem.
I feel if the float level was too high or the needle and seats were leaking then there should be fuel dripping from the boost venturi first.

 

Pulled the carb off car again and removed top .Replaced needle and seat valves,Checked for needle valve under acc pump nozzle and it was there.Cleaned and reinstalled.Also removed acc pump check valve and checked operation. Set all float measurements and reinstalled top.Checked acc pump specs.Reinstalled on car and no more fuel dripping from nozzles! So one of the above was the culprit.Thanks so much for all the help with this problem.I have learned so much from the helpful people on the corvette forum, JEFF