I have a 1964 Ford F-100 that I bought a few years ago. When I bought it it had a Chevy 350 vette engine in it and had the front sub-frame of a 1972 Nova. I supercharged it and raced it for a bit until it spun the bearings in the bottom end.

Having only mopars I knew it would get a mopar mill and I happen to have a fresh 1989 factory roller cam engine with a 4-bbl. on it. I added the exhaust manifolds from one of the 1993+ 5.9L Magnum engines I have laying around (headers will not fit). The engine is just a factory stock rebuild and the truck has a true dual 2.5" exhaust with no H or X pipe yet. The truck runs a stock mopar electronic ignition like the mid 70's cars have and it now has a T/F-727.

My question: The carburetor I used was a brand new Holley 670cfm vacuum secondary unit with an electronic choke. Ever since I put it on it has been trouble some. It always starts and runs good, however the truck gets poor gas mileage. I realize this truck is heavy (~4,000 lbs.) however I think it should be descent. Anyways my big gripe is the hesitation right off idle. I called and talked with a couple techs at Holley and they all say it needs larger squirters. I find that hard to believe being this engine is stock, but it maybe the case I guess.
It smells rich and I thought maybe it is putting too much fuel in the chambers causing the poor fuel economy.

What do you guys think?