I got a 1978 F250 with inline 6 in a trade. The previous owner bought a few wrong parts for it. It's got a brand new carburetor but it has a fuel return port. The tank and the pump don't have a return.

My question is can I just plug that port off or will it not run right? If not, what would be the best/cheapest route to making it work? Am I just better off buying the correct carb?

Also does anyone have a diagram or picture of how the other ports on the carb are plumbed? None of it was hooked up when I got it and all the pictures and diagrams I've seen are for a V8.

 

Any ideas?
Should I just try it with a cap on the return and see what happens?

 

You can try that but if it overfloods you could have a fire under the hood. Which saves you worrying about repairs, but not really the desired result.
Maybe getting the right carb would be a good plan.