2.9/4.0 head differences...

[Harry Rathien]

Been a LOOONG time since I've been here. Hadn't even wanted to look at another 2.9 since my girlfriends ranger burnt to the ground....

but I somehow screwed up and bought me a 1988 BII with title for $125. Par for the course, the heads are cracked.

Been thinking about the 4.0 swap, but don't know if I wanna get into the wiring aspect of it or not. But I have been thinking about a couple of things to do to the 2.9.

I know you can put 2.8 pistons in them and get them up to 10:1 or 10.5:1, but I don't wanna dump premium in my tank if I can help it. However, I also know that 4.0 heads on a 2.9 would decrease the comp. due to larger combustion chambers...

My question is this: Does anyone know what CC the chambers are on the 4.0 heads (91-94)? Im wondering if I could use 4.0 heads with 2.8 pistons and be able to get a boost with the slightly higher compression and larger valves. Any reason this wouldn't work?

Thanks.

-Harry

 

[fastpakr]

I don't know what you'd do about an intake manifold in that situation. The deck height is shorter on the 2.9, so everything is going to be out of alignment when you switch the parts around.

 

[AllanD]

The 4.0 heads also have bigger ports on both sides.

Trust me a 4.0 swap is a lot easier than almost any other swap
on a Ranger.

It would of course be much easier if you had an '89 or 90 Bronco3, but....

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