Carb help should this be plugged?

[JSabah]

A friend came over to help me tune my carbs (which I know nothing about). He discovered a small tube which he thought should be plugged like the others on the carbs.... I noticed 1 carb has the tube and the other doesn’t.  Below are pics of the carbs - one with and one without. The one with has a black tube hose that he added and plugged with a bolt but for the pic I had removed the plug/bolt. What is the port and should it be plugged ... and just out of curiosity, why would one have it and the other not when they are supposed to be the same Motorcraft carburetors? 

[1949 Wraith]

Do you have a vacuum line coming off of either of your carbs to the distrubutor vaccum advance? It looks like they should come off the lowest part of a carb. I would try plugging both holes if you have a vacuum advance line and see if you have any noticable difference in performance.

Edited February 24, 2020 by 1949 Wraith

[greg g]

Do you have any paper work on the carbs?  Looks like the ones Tom Langdon sells through his Stovebolt age.  Might give them a call and ask. When the car is running, does it make a difference if you plug them with your fingers? Can you feel any suction there? Put a piece of tube on each one, plug the tubes with screws. Does it make a difference in how it runs? Where is you distributer vacuum sourced from?

[Adam H P15 D30]

This should help

Weber Vacuum Ports.pdf