85 2.5 to 4.0 swap

I know, I can already hear you furiously typing about how this is a pointless project and to just find a Cherokee that already has 4.0, but hear me out.

We have an 85 sitting around with a 2.5 and we've been on the fence for almost two decades on what to really do with it. I'm finishing up a turbo build on my Sierra and thinking this is my next project.

I have ate, slept, and bled Jeep for over 20 years now but the last few years have really gotten into performance stuff. There's not really anywhere to go in my area that isn't mudding and I am absolutely positively over mud.

We've got a 97 that needs to go to the great boulder field beyond due to rust. I want to shove the engine into the 85 and do a turbo build.

I'm not scared of the fabrication or anything like that, I've just got a simple question. The few people that have taken the time to put a 4.0 in an 84 to 87, how did you do the motor mounts? I know that the 85 was never intended to have the 4.0 and that I'm going to have to do something, I just want an idea or a game plan. I could just set it in there and find out the hard way but it's going to be a minute before I get this project rolling and get that 85 carcass to my shop.

Just looking for ideas and inspiration. Well aware that what somebody else did might not work for me, it just doesn't hurt to sample what other people have done.

going to AW4?

think you're gonna have to mock it up to know.

I'd really like to keep it a five speed truck but I don't have any sitting around. I wouldn't mind trying out the AW4, I've got a few of them sitting around so no worries if I mangle a couple. I've got a built 4l60 that I can't give away, probably wouldn't last long. If I come across a 4L80 for a good deal it might just get that.

Yeah, kind of figured I was just going to have to mock it up. I just know that best case scenario I won't get that 85 to my shop until spring. I really like the layout of good plan well beforehand. ��

Doesn't the '85 come with a AX-4?

Didn't early 4 cylinders come with a shorter nose? might check into that; the 6 is already tight in the later ones.

I did the 85 2.5 to 4L swap. I swapped the hood and front radiator support. I brought over the complete wiring from the firewall forward. I had no big problems. I have the factory service manual with all the wiring and connector info. You will need to swap the radiator as well.

I actually built mine as a stroker before the swap. I now have over 250k on the stroker and love it.

RCP Phx said:

Doesn't the '85 come with a AX-4?

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I can't remember if they came with an ax-4, I know my mj has one though. This particular 85 has an ax-5 but it's going to hit the scrap pile.

Unclewolverine said:

Didn't early 4 cylinders come with a shorter nose? might check into that; the 6 is already tight in the later ones.

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If I remember right the nose itself isn't shorter, the radiator support is definitely different. Radiator support needs to be changed because the 2.5 radiators way closer to the motor and the hood typically needs changed because the radiator support is part of the hood support. Lots of drilling out spot welds.

old_man said:

I did the 85 2.5 to 4L swap. I swapped the hood and front radiator support. I brought over the complete wiring from the firewall forward. I had no big problems. I have the factory service manual with all the wiring and connector info. You will need to swap the radiator as well.

I actually built mine as a stroker before the swap. I now have over 250k on the stroker and love it.

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I'm not worried about all that. I've got a ton of 4.0 harnesses and PCM sitting around and have made a lot of them into standalone harnesses. This is primarily going to be a toy so I'm not going to swap the hood, probably just run hood pins. I think I'm going to run a Honda race radiator and have plenty of room.

I used to run my own shop and after awhile I was primarily swapping newer 4.0s into older Jeeps that had the 4.2L. I was well known for being a Jeep mechanic and had someone approach me that wanted fuel injection in their CJ for drivability. I bought a donor XJ and swapped everything over. Kind of snowballed from there after he got talking with his buddies and I ended up doing a ton of them. Best job I ever had but family issues came up and I needed a job with better benefits and most importantly time to take care of my family.

What did you do with the motor mounts? I've never pulled a 2.8 or a 2.5 then took the time to actually look at the frame rails. Will the mounts sit on the frame rail and I just have to drill holes or am I making plates or what?