carb
 

I have a 780 holley carb that has fuel coming through 1 booster, check the float change the gaskets 6 pounds of fuel pressure. the carb run fine till i put it back on the stocker motor. Changed the carb to another 780 it ran fine till i shut the motor down then restarted it ,same thing. Any guesses?

Re: carb
 

A Holley carb will easily handle 7 1/2 -8 lbs of pressure make sure the float doesn't have fuel in it. Then pull the site plug with pump running and engine running with a rag under the carb to catch spill over you should see fuel at the bottom of the site plug hole, but not running out of the hole unless you rock the car back and forth.

Re: carb
 

I did check that and also changed the float ,the old float weight 14 grams new one 15 grams. it only slubbers fue out of one booster, changed the needle and seat. I Never had this happen in 40 years of holley carbs.

Re: carb
 

Jim if you're talking about dripping after you shut the motor off you just aren't turning your fuel pump off early enough before you shut the motor off in this hot weather. If you are talking about with the engine running either your float level is too high, or your fuel pressure guage is not right

Re: carb
 

Is the mounting surface level on intake side to side?

Re: carb
 

Change both gaskets float bowl side and main body side also replace the the 4 bowl screw gaskets and torque the the bowl screws to 35 in-pounds and your problem should go away.

Re: carb
 

power valve hitting the base plate screw "boss" in the vac. chamber not allowing the m/block gasket to seal to the venturi surface. this is a common problem with "older" venturi's. check a new venturi an you'll see what i mean..

this is also made worse if you are using the new non-compressible p/valve gasket with a mill'd surface of the venturi as they become closer together.

Re: carb
 

o ring on needle and seat

Re: carb
 

No the fuel only comes out when the engine is running, some one suggested check the air bleeds . I did that and that seemed to fix it. Thank for the help.

Re: carb
 

Also check the needle and seat, I've had debris stick in there and prevented it from sealing.

Re: carb
 

HSAB plugged or maybe you have the bowl gasket or metering plate gasket installed incorrectly OR you have the wrong gaskets to start with---a symptom of definitely siphoning fuel out

Re: carb
 

Was one or more of the air bleeds plugged up ?

Re: carb
 

Question: Why would 2 seperate carburetors do the same thing
and the solution be a "plug'd" hi-speed air corrector be the answer?

Technically doesn't make sense unless jim lives in the desert an he doesn't.....

Re: carb
 

Run leak down test on engine. Bet you'll find the problem

Re: carb
 

Not sure if you wrote "its solved" but you can run the engine up to about 2500RPM and put a gloved hand or towel over the carb top when the engine has almost died remove your hand or the towel and let the RPM come back up---do this 2-3 times and see if it clears up ---what you are doing is going from vacuum to siphoning and jostling any particles that may been the bleeds or the idle passages--kinda self cleaning or sloshing process by going back and forth