my 258 do I keep it or get rid of it

[keye]

I just bought a 1986 CJ7 I do beleive its a 4 speed...Have not really checked it out or brought her home yet, I bought and paid cheap sight unseen and I did truely come out ahead in this deal.....its in real deceint shape and this winter I do want to do a frame off....the 258 straight 6 is ceased solid the jeep has sat for the last 6 or so years without being touched it has 220000 kms on her....now I also have a 1990 Cherokee with the 4.0......auto....135000 kms....it runs like a charm...now my question is should I tear down the 258 and do a total rebuild ( which I really do not want to do) or can I swap the 4.0 onto the 86 CJ and also onto the 4 speed and transfer sitting behind the 258 and if so what am I looking at in wiring or anyother problems.....switching the 4.0 is what I really want.....I do beleive this is my 1st out of many more questions this winter

 

[Megamole]

I do not know for sure but I have heard that the bellhousing on the 258 (4.2)and 242 (4.0) are the same so If you had a manual transmission Ax15 they would interchange. Not sure with the transmission you have.

 

[currupt4130]

Yea, just make sure you swap take the bellhousing for the AX15 with it. The T-176 bellhousing wont bolt onto the AX-15. I'd swap the 4.0 in. Expect to run into problems with motor mounts. I'd also order a standalone harness from Painless to swap it in with.

 

[redrooster]

huh?
I think he is just talking about swapping the engine and leaving the CJ transmission in there. The engine should bolt to the bellhousing just fine. Might have to cut a hole for the crank trigger though.

 

[Bounty__Hunter]

Throw the 4.0L in and run it like it is. You'll have to do a little magic to get the intake to bolt up to the 4.0L engine, but thousands before you have done it.

Better yet, rebuild the 4.0L with the 4.2L crank for a 4.6L stroker.

 

[keye]

I thank u all for the replies...just tore off the old rusty body off the Cj today...hopefully another week I can get the frame in for sand blasting, than its me and my mig welder......I am doing a complete frame off and eventually going with a new fiberglass tub.....now for the motor, I have been reading and yes there seems to be some if not many roadblocks with installing the 4.0....maybe I am wrong...but there seems to be much I can do with this 4.2..exhaust..carburation and spark...guess I am tending more now to keeping the 4.2....just do not want to spen the winter trying to swap out and losing my mind in the process.....this ride when done will turn heads, hopefully, but for the most part she will be a daily driver, so maybe with the 4.2 breathing a bit better, might be all I need.......I am and will in the near future rely on the expertise of this community with probably many matters involving this winter project...A thanx to all..................

 

[currupt4130]

If you want something that'll turn heads get an old 360 out of a wagoneer and rebuild it rather than the 4.2

 

[Bounty__Hunter]

401, 401, 401 :twisted:

An AMC v8 will be nearly a bolt-in.

I thought the 4.0L and 4.2L were similar externally, meaning the 4.0L longblock would bolt in the CJ with a little work.

 

[keye]

thats what I was hoping for..like I said in my first post, I have a awsome running 4.0 91 cherokee thats all rusted out sitting long side the house, but bro I am just a regular dude that loves the jeep open concept, from frame to new suspension to the f/glass tub its all like a work of art with nuts and bolts.....so what I am reading is that the 4.0 will align to my 4 speed on there now?????? will have to change or alter the bell housing and the wiring, now the 256 is carburated, the 4.0 is fuel injected, will I be able to use the injection using the 4.0's modules and computers....see this is what I mean, I am totally lost and relying on many questions before starting this project...again, I would rather have the 4.0 but accessorzing the 4.2 would make it so much easier