Hey everyone, I have done some searching, but I have a FEW questions. I am buying an '87/'88(not sure which year yet) Comanche 2wd from a good friend of mine. It has a 2.5 4spd right now. The engine has bent valves,no a/c or p/s, but the body is PERFECT! My plan for the summer/winter is to convert it to an HO 4.0,5spd,4wd,w/ps and ac.....NOW for my questions:
1)Do I have to change the under dash wire harness to convert to HO? What about the instrument cluster? I am already going to have the dash out to add A/C.
2)Do I have to change out the pedal assembly for any of this?
3)Will the 4.0 BOLT in place of the 2.5 without fabricating new mounts?(I will be using the 4.0 motor mounts and frame perches)
ANY info on this will be GREATLY appreciated. Thank You in advance.
-Lance

 

In my opinion you'll need to change the engine compartment and dash harnesses because of the engine differences, the addition of AC, and the need to add the wires for the in tank fuel pump required w/the 4.0L HO. You really need a donor vehicle to get all the wires and different computers you'll need for this swap.JMO
Good luck with the swap, and take lots of pics.

 

I have a NON HO 4.0 donor cherokee available to me if I want. If I go that route, Will I still need to change the wire harness under the dash? Or will the engine harness and computer be the only changes?...Also, the fuel pump? Thank You
-Lance

 

As long as the 4.0L has fuel injection it is the same issue, whether it's an HO or not. This might be helpful. Jeep Wiring diagrams

 

The 4cyl is also fuel injected..?
Cool, Thanks.
-Lance

 

You've got a lot to do for this swap. I would just give up on the 4.0 completely. Its a great engine but with all the fabrication that your gonna do, all the JY shopping why not get a chevy (make me puke) or FORD!!!!(yay) with full width axles and a running small block and swap all that under there. That'll give you a full size drivetrain, small block power, and one BA little cherokee. Rip out all the inside guages and controls and use Lokar cables and electric guages on a painless harness.

I hate it when I ask a question and everyone jumps in a say's well I'd do this instead of answering it, but I've tried what your talking about a couple of times in different vehicles and when you finally get done you look back and think it would have been easier to start with a welder and chromoly tubing and build the whole damn thing from scratch. Consider the amount of work you are doing and think of what that amount of time and labor would get you if you stripped in all down and built it all one of a kind. No wiring to try and make work just all your own stuff man.........

Or maybe thats my dream....

 

I don't mind going ground-up. I am currently building my '78 Chevy 2wd from the ground up to pull my BBQ trailer. But I do have to comply w/smog *****

 

No offense dude but it sounds like you're trying to turn his project into yours, and you don't have a clue as to his level of mechanical knowledge or skill. Not to mention his motivation or finances.

 

There will be a need for extensive firewall modification. The 4 cylinder Comanche has a smaller engine compartment than the 4.0 inline six. If you are mechanically inclined with some good fab skills then go for it. That fact alone has made me pass on a few good MJ deals lately.

 

I thought it was changing out the radiator support...??

 

go to my profile and look at my albums... i have an 87 comanche that i did nearly the same thing... except mine already had the 4.0
but yes, you will need to change engine mounts, and the Entire wire harness should be swapped out of a donor vehicle...
i helped my older brother do his 2.5-4.0 swap and he snagged a wire harness from one of my parts vehicles... its a bit easier than trying to add wires to the circuit..
the 4wd swap thought is fairly easy, you will also need to relocate the crossmember bolts farther back but its not that hard
plz post some pics... my MJ looks like a BA Mo Fo and yours should look just as good...
oh yea and btw while your doing all of this, do the Spring over axle conversion on the rear.. you'll get atleast 5" of lift minimum, and if the leafs are good enough it could be up to 6.5"

 

your best bet on a swap like this is to find a donor vehicle with good drive train other wise you will spend countless hours in the JY searching unless your like some of us and like searching through old piles of crap

 

Thanks Guys!... And YES pick a part is like Disneyland........The Happiest Place on Earth!
-Lance
BTW I do have a complete donor vehicle w/ a NON HO 4.0 and 5spd/231. I also have a D44 available from a 87 Cherokee if I want to do the SOA.

 

WOW, it's been a long time since I posted on this topic. Plans have changed and now I have a '95 XJ.
My plans for the MJ are Grand Wagoneer D44's, 4.6 stroker,automatic and 231. I want to make a nice camping/fishing truck for my two boys and I. Hopefully I will get some pics of both up soon.
-Lance