Hey guys, my holley 750 VS. has developed a leak, it only seems to leak when the car is first shut off, it leaks from the secondary shaft (where the vacuum unit is attached), until the rear bowl is empty. i have opened the carb up and can't find any sign of where it could come from, all the gaskets are new and the bolts/screws are tight. I don't see any cracks or anything obvious for causing the leak but it runs down onto the intake and into the intake which makes the motor hard to restart (flooded). any body have a similar problem that can clue me in??

I have checked the fuel level when running but I don't see how too high of a level could make it drain the entire bowl when off.

 

Looking through my Holley book I can see all the fuel passages go up through the metering block so leaking down can't come from them. If nothing is cracked, there's only one place that fuel can drain from the float bowl into the engine.

Check the power valves. They dump fuel straight down under the carb into the intake and not into the venturi like all the other fuel circuits.

My guess is that either a power valve gasket is leaking or the diaphram of the power valve itself is broken. Pop a new power valve into it and see if the leak stops.

 

If it's leaking by the vaccum diaphram for the secondaries I would probably rule out the power valve since the Holley VS only have the 1 in the front metering block and nothing in the back. It would explain the flooding condition, but where is the leak coming from in the back?