I have a 1990 I6 EFI w/ 5speed tranny. It has 200K+ miles and other than routine maintenance it has had no work done. I want more power and want to stay EFI. I can pick up a 1995 351W from a local junkyard to rebuild and install. Doing all the work myself. What is needed to install. I see posts of EFI to carb and carb to carb but no EFI to EFI. Is this a worth wild swap. I will be P&P the heads and intake and a slightly bigger cam. Not sure what 5-speed I have and what it takes to bolt it to a 351W. Not sure what motor mounts I need. Not sure what computer I need. Not sure what wiring harness I need.

Any help will be greatly appreciated.

 

Get as much wiring & accessories as you can from the donor truck, including the engine mounts, frame perches, radiator, engine bay harness, & Y-pipe. If the '95 is MAF (single outlet on the air filter), you score bonus points.

 

Should he bother with grabbing the 95 model electronics?

This is pretty likely going to be OBD2, which I wouldn't see as being a help there...

I personally would just find a 1990 or other very close year 351w harness to be safe. Plug it right into the firewall and call it a day.

The engine will bolt to the trans as the I6 and both v8s have the same bolt pattern, but I'm not sure what flywheel balance is called for, but a shop can do that up for you.

Then again, a stock 351 may not grenade a mazda trans...a built engine, I'm not betting the house on that. Find a ZF5 (pricey piece, even when needing a rebuild) from an occasional F-150 or mainly in the HD trucks and slap that in place. You won't get crisp shifts from a ZF, though.

 

No, it's not OBD-II. That started in '96. I swapped a '95 engine, wiring, & computer into my '83 Bronco.

He should use a stock '95 5.8L flywheel.

Ford never put a Mazda behind a 5.8L, but many people have. As long as it's not used for towing or large tires, AND it's scrupulously maintained, it'll be OK (as much as any Mazda box can be "OK").

 

Alright I found a place that has a 351W from a 93 bronco and a 351W from a 93 F350 Dually. Is one better than other or all the same. They are about half the price of the 95 351W.

 

If your '90 is a 1/2-ton, then the Bronco engine & wiring would be better. If the '90 is heavier, I'd go with the F350 stuff. Whichever way you go, try to keep it all stock from one truck so it's easier to work on & buy parts for.

BTW
EFI engines are commonly referred to by their metric size, to differentiate them from carb engines. So "351W" typically means carbed - yours is EFI, so it's better to call it a 5.8L.