Interested in building a light weight, fuel efficient 73-79 F100. Have the opportunity to pick up a solid running 250 sixer. Is this a good option for this project?

 

Sure. But it was never offered in a F100. Instead, a 240 six will bolt in and be heavier duty.

 

The truck will be basic transportation. I will be reducing weight and attempting to get it to around 25 MPG. I have no experience with Ford sixes aside from the 300. This engine is in a Maverick and is essentially free, other wise I wouldn't be interested.

 

As I said it can be made to work. But the difference in fuel economy of a 250 and a 240 will be small versus the difficulty in cobbling in the 250 with trans linkage, radiator, transmission mounts, throttle linkage, motor mounts and miriad little other things makes the 240 a better choice. With a little parts counter help everything is available from Ford to bolt in the 240.

Your biggest MPG gains will come from chassis prep: tire sizes, gear ratios, aerodynamic aids, stuff like that that has been discussed elsewhere ad nausium.

As a teenager I once had a chance to get a Falcon convert and a free 272 Y-block. I made plans to swap in that dynosaur of a motor. I thank God it never came to pass.

Sometimes free isn't cheap enough to be practical.