Holley gurus: ID a leaking port please!

[Manifold]

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

 

[Manifold]

As I cross-posted this on a few boards (I was desperate for some help), I got an answer for anyone interested. That port feeds the timed vacuum port which is found on the standard primary metering block. The Proform block I have does not have this provision, and sometimes with these aftermarket pieces or non-timed vacuum port equipped blocks, you will get fuel leaking out of this passage. Plugging up this port at the metering block face of the main body will eliminate the leaking.

 

[Manifold]

Looks to me that a previous owner never installed the Proform metering block gasket, or installed a used Holley gasket. The hole in the Holley gasket for the bottom of the channel for the timed spark port just cuts into the bottom of the (IIRC) idle or emulsion well - in other words, it's open to a part of the metering block it isn't supposed to be. I've attached some pictures in case someone else runs into this problem of fuel draining from the carb regardless of being in use or not.

I suppose the proper fix is to get the correct gasket, but AFAIK none of the stores near by carry the Proform gaskets. Though, they carry the Holley gaskets. So, I decided to seal off the passage and use Holley gaskets.

Holley metering block gasket used with Proform block. Gasket still has impression from original metering block with timed spark port provision (marked in yellow). The overlap of the bottom hole in the gasket for the timed spark port and the impression in the gasket from the bottom of the well marked in red.

Metering block with the gasket shadow/residue showing the small portion of the hole overlapping the bottom of the well:

New Holley metering block gasket set onto Proform metering block. I marked where the fuel was leaking in - you can see the overlap.

Stock photo of Proform gasket with no hole for the timed spark port. If this gasket had been used, this problem would have not existed.

 

[65-440]

nice find ..... damn proform !! haha ! ....

 

[Revhendo]

Outstanding find. That's the type of stuff that drives me nuts for days.
(Like I need help).