I just bought a '78 Bronco with a rebuilt 351M. The only real upgrade done to the engine was desmogging, but the prior owner decided to stick an Edelbrock 4bbl intake and carb on it. I planned to get a 2bbl adapter and Motorcraft carb, but the Holley 2bbl is about $100 cheaper. Does the Holley have comparable off-road performance?

 

I'm using an auto lite 2100 off a 69' 351w but I put it on a 260 sbf with roller cam conversion. It's a good carb and easy to fool with. Just pop the top and make sum adjustments and you don't have to worry about spilling fuel or disconnecting lines or linkage.

 

A good 4bbl should get the same or even better mpg's as a 2 bbl. It's all in the size of the carb, it's jetting, and if a vaccum or mechanical secondary throttle. Also it helps if you don't floor it but the extra power can be habit forming.

 

Seems to me serious off roaders prefer eddies over holley for some reason, something to do with the float and fuel starvation at extreme angles. If you're just poking around it probably doesn't matter. Sideways on the slickrock around Moab, maybe.

 

I run a 2150 on my 390 on my high boy in the mudpit and I am competitive with the 4 bbl guys. They don't believe it. Blend the body and jet it. The biggest jets they produce factory for that carb are 62's. So what do you do? Break out the drill bits. It is only brass. Trust me it works!!! Just be patient and go slow it WILL work!.

 

Is that an autolite, the 2150 or holley?

 

2150 is a motorcraft carb.

 

2V carbs with the right manifolds, etc. are excellent performers...Pat Musi won the NHRA championship 1 year running 2V carbs...Holley even built (years ago) the infamous 2V 650 cfm carb (#6425)!!!!!

The 500 cfm Holley 2 bbl is exactly half of a 750 cfm double pumper Holley 4 bbl...and the 500 cfm unit runs the 50cc pump which really works nice on eliminating the transition!

 

. Guys in the '335' engine forum below will gladly swap you a 2 bbl. carb. and intake for your 4 bbl. carb. and intake...