'75 401 Running Now, but very Rough!

[Rocjeepn]

OK... Recently purchased my '75 J10 with the 401. Recently replaced the original Motorcraft Carb with a reman stock Motorcraft with new gaskets. Replaced the cap and rotor due to age as well. Installed all new vacuum hoses and I do think they are all in the proper spots. She will fire right up, but really does not want to stay running. And if you try to give it any gas, she either really wants to stall, or will stall. Exhaust reaks. Sounds like an air sucking sound, plus she will let off a little back fire every now and then. If I am able to keep it feathered and running for a little bit, I can now and then get the RPMS humming, revving it up. But that is rare. I am at a loss as to what my next step should be. Timing? More Vacuum issues? Anyone live in the NW Phoenix area that would want to take a look?

[68glad]

I'd verify timing first.

[AwesomeJ10]

You say there is an 'air sucking sound'.

Are you sure there are no vacuum leaks? Get a fire extinguisher and a can of starting fluid. Start the engine and then spray starting fluid all around. When the engine rpm's go up, you've found the vacuum leak.

[Ristow]

popping thru the carb,out out the pipe.

[shimniok]

Whenever exhaust reeked it was due to running crazy rich. If it's rich it could stall when jamming on the gas, otherwise it's usually more likely that it'll bog down and eventually clear out and rev up. Overly lean seems to want to "flame out" when you jam on the gas, occasionally resulting in popping out the carb.