I picked up a used Holley Street Avenger 770 which has a primary Proform billet metering block. Not sure if this problem existed the whole time or not (though, I suspect it did), but it is leaking while simply sitting even when not on the engine. The leak was coming from the front passenger corner of the carb and appears to be the source of a problem I was chasing down. After I ensured the front bowl and metering block were snug, I checked to see if the leak disappeared but it didn't. It was coming from inside the passenger side primary venturi. I removed the base plate and filled the bowls back up. I figured out which port is leaking, but I don't know its purpose. I poured over two Holley books I have, but do not know what this port is. The only thought I had was the power valve had gone bad and was leaking, but I see the built-in power valve protection and figured this fed the valve and the port in question wasn't connected to that circuit. I verified several times the float levels were correct.

I took several pictures of both the bottom of the main body and the body side of the base plate. I've marked the port from where the gas is leaking. If someone would clue me in on what this port is and what I need to do to get it to stop leaking, I would greatly appreciate it. I'd like to make the last test-n-tune session this Wednesday with this carb (I pulled off a Carter AFB 625 in favor of the Holley) to see if I can dial it in some and run quicker.

Thanks for any insight anyone out there may have!

Bottom of main body (If I should remove the gasket for easier identification, then I will but would rather not if possible)


Closeup of bottom of main body


Main body side of base plate


Closeup of base plate