4.0 Swap

[B2Mann]

Ive been thinking about doing a 4.0 swap in my 1990 bronco II that has a 2.9. Ive been looking at a few motors and was curious, Ive heard a few people say that the 4.0 block has changed a little over the years. Is there a specific year that I want to pull a 4.0 from?? And will I be able to reuse my 5speed tranny with the 4.0? I also know the clutch disk is different between the 2 trucks.

 

[sammthehamm]

I am doing the same swap right now to my 87 bii

 

[B2Mann]

Hows the swap coming?? I hear everyone saying that there B2 has trouble holding a constant high speed. My B2 has the 2.9, 4x4 and can hold 75-80 with no problem. No change in the gas mileage either. The rims are an inch bigger and the tires are bigger as well. Runs great and doesnt get hot. I understand that the 4.0 has more torque but the 2.9 isnt a dog in any way.

 

[86nevadaBronco]

To do the swap, you will want the non SOHC 4.0. You want the OHV 4.0. The 5 speeds will fit between the 2.9, and 4.0 with little mods. The original 2.9 clutch/flywheel/starter will work, but are smaller than the 4.0 by 2 inches. If you get the 4.0 from a manual trans ranger/explorer and want the bigger clutch, than keep the 4.0 clutch, flywheel, starter, and engine spacer. I've just finished the Explorer 5spd M5OD-R1 trans swap on my 86. Aside from changing drivelines to 88-later ones, and new ***** cylinder.....the trans bolted to the 2.9 with no problems using the original size clutch.