It was directed at the OP. However, 8 mpg for a regular or mild 390 is pretty low.

I could easily get 12+ in my dual quad 428 on the highway. Commuting back and forth to work was around 10-11 mpg.

Josh

 

So would it be worth while to just rebuild the 390

 

To do the swap you'll need:

351 Engine
Transmission
Engine perches
Mounts
All accessory brackets
Possible Front and Rear driveshafts
Exhaust

It isn't as simple as yanking the FE and throwing in the Windsor.

Josh

 

Ya I figured it would take a lot of work. My question is. Would it be worth that trouble or would it be worth rebuilding the 390?

 

I'm biased. I bleed FE engines, but I drink diesel.

Josh

P.S. That reminds me I need to do something about this 2.9 gasser in my Ranger...

 

Diesel swap! 6.9 or 7.3 idi needs to go in there!

 

I'd do a diesel but it would be a lot more work and alot more money!

 

dont know about the support stands. research indicates the 67-79 302 uses the same supports as the 77-79 351M/400. (Thanks Bill ) Should be a mount swap. agreed on the rest of the pieces. What about an adapter to run a 4R70 or 4R100 behind the FE???

 

FE/I6
Small block
335/385

Josh

 

Do they make adapters to put a zf5 on a 390?

 

Easier to adapt an NV4500

Josh

 

Ya I was reading on that earlier this mornin

 

Ok. Which motor has more horsepower off the showroom floor between the 390 and 351w in truck bodies only?