[Lew Silverman]

Is this the hole you're talking about, Chris?

It's the vacuum port for the power-valve, so I'd make sure the valve and gasket were good. The metering block itself could have a bad gasket but I agree with Myron that it's unlikely to be warped badly enough to leak.

I also think that the later model Holley's were modified with a o-ringed transfer tube for the accelerator pump shot through the metering block and of course the gasket was changed to accommodate it. If you use that gasket with the older metering block you'll get a leak for sure!

Good Luck finding the problem!

Lew