engine swap for better mpg

[midmodeeredriver]

I have a 79 F20 with a 400. It"s my dalily driver around the farm and from feild to feild. The truck is great but it is a gas guzzling machine. Could I remove the 400 and put a 302 or a 300 strait 6 and get better fuel mileage. Would either one fit up to my auto trans and fit into my motor mounts or would it be more work than it's worth. also is the 400 motor worth very much. I didn't build it but I know it was built up pretty good. Thanks for any input. I'm brand new to the site. Thanks.

 

[Alvin in AZ]

I have a 79 F20 with a 400. It"s my dalily driver around the farm and from
field to field. The truck is great but it is a gas guzzling machine. Could I
remove the 400 and put a 302 or a 300 strait 6 and get better fuel mileage.
Would either one fit up to my auto trans and fit into my motor mounts or
would it be more work than it's worth.
also is the 400 motor worth very much{?}
I didn't build it but I know it was built up pretty good.

The 400's original cam timing sucked donkey dick. :/

Retarded timing makes it need more gas to do the same work.

Advancing the timing moves the power band lower in the RPMs.

Peak horsepower (but pipey like a 2 stroke) is increased by the
retarded "smog" cam timing too tho.

The retard is in the timing gears.

Check the cam timing on it before swapping it out?

Yes the 351m and 400 are good engines but their "smog" cam
timing ruined their reputation among those that don't know any
better than to believe the "common knowledge".

"do your own thinking"

Alvin in AZ