The Ford Barn

PC/SR · 11-26-2012, 06:59 PM

I have dual 92's on a Model A Speedster. Doing some timing and vacuum checks the other day, and noticed that at 2300 rpm gasoline started leaking down the vertical shafts that go up into the carb body that actuate the accelerator pump. Does this on both carbs. Below about 2200 the flow stops.
They were rebuilt last year with new throttle shafts, gaskets, etc. No leakage from throttle shafts. I have an electric fuel pump, 2 lbs psi at the carbs. Float height is correct, with no leakage anywhere when just running the fuel pump with engine off, or running up to 2300 rpm. It has a hot cam, and very slight flutter, less than an inch, on the vac gauge at 2300. Max timing is 27* advance at 2700 rpm, an FSI mechanical advance distributor.
Again, the leak comes down the vertical shaft out of the carb body, not the throttle shafts or anywhere else.
I dont get it. Anyone else hear of this, have any ideas? The 94’s were built virtually the same way so any experience with them might give a clue. Thanks for your thoughts.

11-26-2012, 06:59 PM	#1
PC/SR Senior Member Join Date: May 2010 Location: Santa Rosa, CA Posts: 1,285	Holley 92 carb leak I have dual 92's on a Model A Speedster. Doing some timing and vacuum checks the other day, and noticed that at 2300 rpm gasoline started leaking down the vertical shafts that go up into the carb body that actuate the accelerator pump. Does this on both carbs. Below about 2200 the flow stops. They were rebuilt last year with new throttle shafts, gaskets, etc. No leakage from throttle shafts. I have an electric fuel pump, 2 lbs psi at the carbs. Float height is correct, with no leakage anywhere when just running the fuel pump with engine off, or running up to 2300 rpm. It has a hot cam, and very slight flutter, less than an inch, on the vac gauge at 2300. Max timing is 27* advance at 2700 rpm, an FSI mechanical advance distributor. Again, the leak comes down the vertical shaft out of the carb body, not the throttle shafts or anywhere else. I dont get it. Anyone else hear of this, have any ideas? The 94’s were built virtually the same way so any experience with them might give a clue. Thanks for your thoughts.