Quadrajet question
 

I have a vacuum port on the top backside of the carb that's capped and a line that's capped. The line goes to manifold vacuum and the other branch on it runs the climate control on my Caddilac. The motor is a 472. I assume the capped ends should be united by a hose right? Also, what is the purpose of the port on the carb? Thanks

Re: Quadrajet question
 

Q-Jets were installed on a wide range of vehicles. Not at all uncommon for a port to be plugged from the factory or after a carb rebuilt.

If the line with the capped T is otherwise working, the T could be a PO's answer to mis-matched hose sizes or the only hose connector available at the time. Or could be for something since removed.

If the climate control is working, I would replace the T with the appropriate connector and call it good and just leave the carb port capped.

Re: Quadrajet question
 

That should be a vent port to vent vapor of some type over into the carb.

Re: Quadrajet question
 

yeah? I better have a look at the bottom of the air filter housing and see if there's an open hose barb under there.