carb install
 

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.

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...

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 .