2.5 engine swap?????

Can I swap a 94 2.5 with a 85 2.5?

Since no one is answering, I guess this must have been a pretty stupid question.

I'm the one that bought the no oil pressure dandy of a 94xj.

I guess what I'm trying to get at, is my 85 xj has a good 2.5 moter that I want to put into my newer 94 xj that has a 2.5. I was told that my 85 has an AMC engine, and that my 94 is a chrysler engine. Heres where my stupidity comes into play. Thats why I'm asking about the swap. are these two different engines compatable in the 94 xj?

Or do I just take the advise of the last person that answered my (continued oil pressure problem thread) and sell the 94 while I've got the chance.

I would like to keep the 94 because of the safety of the vehicle compared to the lack of safety of the 85. Ecspecially with two young kids involved.

Why not upgrade and install a 4.0L They can be had for cheap. Possibly find yourself a donor wrecked 91-95 XJ and swap everything over.

If the internals are the same, then I'd go ahead and use the engine block from the 85. AFAIK the 2.5 used in the XJ was the same through all of the year changes; only the cylinder head & fuel intake changed.

Swapping engines from a 2.5 to a 4.0 is a lot of work, or so I've heard/read. Besides, the 2.5 isn't too bad with smaller tires.

Beside the point, but I am curious why you consider the 94 to be safer than the 85. Better brakes for one.

I guess your basic question is will the 85 motor just drop in as respects motor mounts and will it mate up with the transmission.

Beyond that you have the doable task of switching the fuel system to accommodate the carbed motor.

If your 85 is stock, you would have to bring the computer, harness and ignition module over, not too big a job.

Since the fuel system for fuel injection is already in place in the 94, how about converting the 85 motor to throttle body injection? Not sure what cost of the conversion runs these days but I guess for that expenditure you could just rebuild the 94 engine.

I think the 94's are safer as well. It's the first year they started installing side impact beams in the doors, and they beefed up the roof support pillars for roll resistance.

Won't the cylinder head just bolt on? If it does, there's no need to convert anything.

I think the blocks are the same. Why would you swap the computers and everything. Just swap the short block. Inspect you head, and if it is fine then just reuse it and all the sensors and computer.

then you can bore over and rebuild the 94 2.5 and put it back in the '85. Have 2 running XJs

well i hope the 94 fits in the 84 or what ever lol. i just got a 94 2.5 out of a wrangler for my 86 hehe. waiting on megasquirt to come out with he sefi computer

BenDiesel said:

well i hope the 94 fits in the 84 or what ever lol. i just got a 94 2.5 out of a wrangler for my 86 hehe. waiting on megasquirt to come out with he sefi computer

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you do not happen to have any fuel tables or anything of the like for tuning do you. I have some for a 4.0 but no map tables for the 2.5. PM if you do. I am wanting to do the same thing on a street MJ I am building.

Pelican said:

Beside the point, but I am curious why you consider the 94 to be safer than the 85. Better brakes for one. .

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Safer, mainly for the fact that the 85 has been abused and still ticking. To many problems with it to take the kids and wife in safely. I don't worry about it when I am by my self fiddle-fart'n around.

Pelican, you asked- (Quote)Since the fuel system for fuel injection is already in place in the 94, how about converting the 85 motor to throttle body injection? (Quote)
The 85 is allready Throttle body injected. Will that make a difference?

The guys have some good points about just swapping the heads. I know there are some slight differences between the 84-85 and later models (valve and ring specs e.g.) but assume the heads will match. Sounds like the way to go, all things reasonably equal.

To the best of my knowledge, no 85 came from the factory with TBI. Stranger things have happened with early xjs but my guess is that if you have TBI on an 85, someone converted it.

Have to admit I know nothing about upgraded body safety features of the 94. My 93 reminds me of a tin can compared to my 85 but that probably has more to do with insulation than anything else. I was thinking more about mechanical features such as brakes and steering. I believe the 94 has better brakes but of course can't actually remember what braking was like 23 years ago when the 85 was new. I also think the steering is a bit better on the 93. Aside from specifics, I understand exactly what scottcolwell is saying about these ancient beasts and transporting family. I guess I was reacting to "lack of safety of the 85". We hauled our daughter all over the country in the 85, and she later hauled herself, from age two till she went off to college and I never once was worried about safety issues specific to the xj. But I would definitely have the same concerns scottcolwell is having if we were starting out today with the jeep in the condition it was in last summer when I finally gave up and sent it off to the yard.

This is interesting -- keep us posted as you move along.

wolfpackjeeper said:

you do not happen to have any fuel tables or anything of the like for tuning do you. I have some for a 4.0 but no map tables for the 2.5. PM if you do. I am wanting to do the same thing on a street MJ I am building.

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nope. i been waiting on them to come out with the sequential mpfi and coil per plug before i start fiddling with it. but im sure you can go to their forum and find some one who has something simular
http://www.msefi.com/index.php

right now as far as i can tell they just sent out some of teh beta units. so its still a little way off.

Yes it'll work...

You have to have an 86+ though, otherwise it's carb'd.

Believe me, I know it'll work... don't ask unless you want a long story (or a link to a thread I need to update).

On another note, it's possible that you will get a small gain of power from the older motor, my FSM's point out that all MPI Engines will have a 9.1:1 compression ratio, while TBI has 9.2:1. not sure what it might do for ya, but I'll tell you if it makes a difference (other than the brand new rebuild and MPI upgrade, ha) for me.

Also, the older cams are different... not by much, but they ARE different.

Might have to change the timing cover, doubt it though. I know the crank pulley will have to be swapped over, but everything else should bolt up fine... Oh wait, no the timing marks on the timing cover get in the way of the water pump a little, might as well swap over the cover unless you want to grind off some soft aluminum (I did). Oh, that leads me to another thought; alternator and A/C mounts. The points attached to the timing chain cover and block have a different thread and such, they may have to be drilled and rethreaded (Mine kinda worked right).

Um... yeah, just keep all the externals from your 94 and it should work with a little finegaling... much easier than a 4.0 swap, believe me I've researched it (although it's easier on your 94 than my 86).

Thanks Mr. Random, I appreciate it. O, got to looking and yes it is an 86 after all. Silly ole me:jester:
Pelican had thought the same thing about the year.

Mr. Random, do I swap out the heads for the direct injection or just keep the tbi?