That estimate should be obtainable. Much depends on the condition of your truck/engine as well as your driving style.

Take a look at this link to get some ideas. https://www.ford-trucks.com/forums/1...-4-9l-mpg.html

 

That's very helpful!!! Thanks!

 

Somewhere between 10 & 20 mpg.

 

Nobody likes paying for exhaust work. But most everybody does because it makes a big difference in performance.

Seriously, you should get a set of EFI exhaust manifolds first. You should notice the difference even with the stock intake and feedback carb. Then shop around for an Offy or Clifford intake and a carb.

There are folks who've claimed near 20mpg keeping it at 60 mph on the highway. I'd probably get closer to 12mpg in the same truck since highway speed on a Texas interstate is around 80. Especially in an F250. That's a tall, heavy truck. What kind of mileage are you getting now?

 

I just bought it. I have not driven it. I need to put another brake booster on it.

 

10mpg if any thing more than that good for you... mine 100% stock and new got 19 on the highway back in '86

 

how was it geared?

 

I have a 4.11 gear ratio and I have achieved 19 mpg once. I wasn't going much over 60 at all.

 

It should be noted that my average is 11 - 12 around town and 14-15 highway.