Hi, I was just curious what the MPG of a 1971 f250 highboy with 33s a 4 speed and a rebuilt 390 would get?

 

I would say for a 4x4 with no OD and a 390 10 would be good possibly better.

 

yeah 10 mpg is about right .

 

I would agree. maybe a little better, but not much. these trucks are heavy, have the aerodynamics of a brick, and the extra weight of the transfer case, front driveshaft etc.

Jim

 

A clay or concrete brick? I'd say the aerodynamic efficiency of a Bump is comparable to a house.

4x for around 10 mpg. A hair more if ya got a really light right foot and a 2bbl carb. But these are Man-trucks so you'll never want to shave your chest, watch Glee, or hold your girlie's purse while she shops.. unless she tells you to!

 

ive got a 68 f-100 custom cab, with the 390. i get 8 mpg, that if im doing like 50 on the high way for more than 10 minutes.

 

Would putting headers and some nice exhaust help on MPG?

 

header's and exhaust can help a little, but not a huge amount. i have flowtech headers, dual 2.5" running to separate flowmaster 40 series and 2.5" running to the back. I get about 8 mpg at best. these curvy, narrow roads and speed limits of 55 are what kill my gas mileage. oh yeah and my motor is also a 390

 

Using my accurate electronic speedometer got 14.2 over a 500 mile run, hills & flat roads
Speeds was 50-60 most the way, did not push it. I have 33" tires 5spd od tachs 1900 rpm at 60mph, In 4th gear tachs 2600 at 60 . shorty Headers with 2.5 pipe & 09 GT mustang mufflers 600 cfm Holley #68 jets. Most carbs can be jet-ed down if your not going to be doing towing or heavy hauling. As these trucks were jetted for all types of driving in all parts of the country..
orich