carb install

[rugger]

I have a couple of questions regarding my carb install. It is off of an 82 305 and is a rochester Qjet. I can figure out all of the vacuum connections but can't fugure out what the large threaded input is at the back on the bottom. Can anyone show a pic of the back of a similar carb? Is there supposed to be a plug in this port? My second question is about the fuel pump. I have the line going to the carb but there is an extra output on this too. Does this connect to the back of my carb? The old engine was a 292 1 barrel so the fuel system is still set up for that truck.

[william 70 c/20]

the port on the back of the carb is a vaccuum port...run the motor and listen for air going through it...you must plug it if you aren't using it...fuel pump may have a fitting for a return line...when pump reaches design pressure it sends excess fuel back to tank...

[jose]

The port on the back of the carb is for your brake booster if it has power brakes if not plug it up . Older model carbs didn't have the return line going to the carb . Don't know what year that changed though . If your carb doesn't have the extra line to hook up the return line then you might want to plug it or change out your fuel pump . The older fuel pumps 72 and up had two lines goin in and one going to the carb .