What is the projected gas mileage on a 1983 f150 4X4 with a 5.8?

 

hard to say with no info

 

You could be looking at anywhere from 10-15mpg, depending on whatever you have done or have not done to the motor

 

My '84 F150 351W, 4X4, w/ C-6 trans. runs 10-12 MPG.

 

Too many variables. Trans, final drive ratio, carb, tire size, etc..

On my '86 with 351w, c-6 3.50 gear, 31 tires, was at 8 with stock carb. Switched to Edelbrock 1406 and Stealth intake and now at 10-11.

 

Yep, too many variables. But, the '82 F150 I sold had a brand new 351W built by me with a Comp Cams low RPM torque cam, ported heads, polished valves, factory 2bbl intake, 2150 carb, and true-dual exhausts with no cat and glass packs. And, the running gear was a C6 with 3.50's and 30 x 9.5 tires. Running light at a true 60 MPH it got 13 on the highway.

Oddly enough, before I rebuilt it, ported the heads, and put the dual exhaust on it got the same mileage. Yes, the power was much better after the changes, but true MPG didn't change a bit. So, I seriously doubt all those who say that opening up the exhaust saves big on gas mileage. Been there, done that, and saw no change.