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Very close! It doesn't feed the port on the base plate, as that hole leads directly into the venturi. But since I was desperate for some help, I cross-posted this on a few boards and got an answer. That port feeds the timed vacuum port which is found on the side of a standard Holley 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. I was considering losing the race-oriented tuned block (67150C) for a standard block (67166C) to get the timed port back, so I may just swap the block instead of plugging. I suppose I could plug it with some epoxy which could later be drilled back out should I swap the block out.

I'm just glad the problem I was chasing wasn't a bad head gasket or cracked block/head. One bank was sounding sick and emitting white smoke/steam on startup. Instead of burning coolant, it was trying to burn off all the fuel. I best check the oil to see if it is thinned out from the fuel.

Thanks for your help.



Be careful with the type of epoxy you use , many are not alcohol friendly and the leak will soon return.


I used some JB Weld. I'm not running alcohol, just regular gas. JB Weld should be fine AFAIK. I've used it on carbs in the past with no issues.

Here's what I found on my carb. 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.