MPG and Manifold Vacuum

[Ziegelsteinfaust]

First and foremost rpm does not dictate mpg. The vehicle in all its Glory, and set up determine mpg. Of your trucks needs 50 hp to move down the road it's needs 50. Either a 230 I6 at 2700rpm or a 350 at 2200.

2 guys I knew had 4x4's on 35" tires. One had a 283, and the other a 396. Both were full bolt on's with cams. On the hwy they got the same mpg, but once on the dirt the 283 litterly got twice the mpg.

I would re gear the rear to get my highway rpm to 2500 at least.

Carbs unlike EFI are less tolerant to rpm/mpg formula. Carbs need air velocity to keep fuel atomized.