2gc help

I have a Rochester 2gc I need help identifying the right hand side port on this carb. I know the left side in this picture is fuel inlet. The right side port I have blocked off but can figure out if it need to be hooked to vacuum or if I can leave it plugged off. Thanks in advance for the help.

 

It's a float bowl vent don't block it off. Early carbs just vented it to atmosphere yours was hooked into a charcoal canister system.

 

Yep ^^^^

If the fumes bother you run a line down to the pan rail. or into the fender well.

 

Since I have it blocked is that possibly causing my off idle stumble?

 

Not likely. But you might "run out of gas" before the needle valve opens.

 

I used to put a disposable plastic fuel filter on it so it would still vent but wouldn't inhale any underhood dirt.