Got questions?
We’ve got the answers—the Summit Racing tech department tackles your automotive-related conundrums. This week, we’re examining the pros and cons of a Ford 390FE engine rebuild.
Q: I’ve got a line on a freshly rebuilt Ford 289 that I’d like to drop in to my old F-100. Currently, the truck has a 390FE engine and a C-6 transmission. I know I’ll need motor mounts, and the transmission might be a problem. When I’m finished, I’d like the F-100 to be somewhat fuel-efficient. Do you think this engine swap is a good idea?
J.S. El Paso, TX
A: The engine swap can be done, but it’s not going to be easy and it’ll take some fabrication. Along with the new motor mounts, you’ll also need a new oil pan and pickup, plus you’ll probably have to modify a set of small block headers from a newer truck. We’d suggest you freshen up that 390 instead. With the correct rebuild, it’ll get comparable mileage around town and have more power on tap for towing. If you opt to go that route, you’ll find some good ideas in SA Design’s How to Build Max-Performance Ford FE Engines.
Tranny won’t bolt up to 289 from a 390. Get motor mounts and stands that bolt to frame for a 302. And headers for a 302 for a 1970 will bolt right up with no modifications.
Why on earth would you ever replace a FE with a small block…. They’re good engines, but the power to MPG difference, plus all the money for the swap is just a waste of time. Enjoy the extra power you already have.
If you do the engine swap you will run into more money than you would if you just rebuilt the original 390. Stick with the rebuild, besides then you have bragging rights as to what YOU put into it.
If your going to tow something heavy a lot, then stick with the FE , the 390 has a lot of torque, the horsepower can be made on the 289, and I think the mpg’s will be much better with the 289. Go with a nice cam and don’t over carb it, 600 max on the CFM!.. Aod trans will make a big difference in mpg, or a 5 spd manual.
A. 390 from a car or a rebuild using 9:1 pistons and an efficient cam, good Edelbrock heads and RPM intake with an AFB or AVS carb and headers, you will be able to get 289/302 mileage and efficiency. This combination will also be able to pull a house down. You will enjoy the torque and if you keep the throttle light the mileage will surprise you.