Need help with a 2.5 Jeep engine.

I bought a Jeep Fleetvan a while back for $700, sold the Toyota engine and auto tranny for $500. My friend had a Mazda 2.2 with a 5 speed that came out of his baby pickup, said he just pulled it out. He wanted to swap for a disassembled motorcycle I had.

He picked up the bike and two weeks later dropped off the engine/tranny. No alternator, flywheel, starter, coil, fan, pullies; you get the idea. It would take $400 to get back up.

I found a 1991 Jeep 2.5 litre with an AX5/NP231 tranny for $250. The engine is a throttle body unit, I'd like to put on the 2 bbl Weber.

Do you have a good source for Jeep aftermarket parts? Do you know anything about this engine? It's been around forever, but are the foibles?

Thanks, Dan

http://www.quadratec.com is pretty good and they have nice exploded diagrams of systems if you know what jeep to search in.

Cliffordperformance.com (I think) has Jeep inline stuff, 4 and 6. Personally, I'd keep EFI though. Those motors ask for nothing other than oil and a battery.

Another vote for keeping the EFI, if for no other reason than to keep gas fumes out of the van.

The AX5 is weak, but I doubt that you'll damage it in that application.

You're not keeping the 231 in the system are you?

Dan,

My understanding of the Jeep 2.5 is it's a 4.0 missing 2 cylinders. There isn't much aftermarket support for them.

I have a 2WD '87 Comanche with a dead 2.5 in it. It ate a cam. Around here seems like all the used 2.5's are either $300 for one that needs rebuilt, or $800-up for a running one with over 150K on it.

In good running order they are fine motors. Not exactly a powerhouse, but good. They were used in the 4cyl Dakotas starting in '95 or '96 when the Dodge 2.5 went out of production.

I had thought about rebuilding mine and converting it over to the later multiport intake and using Megasquirt.

Current plan is to combine Pat & Dave's worlds by stuffing a turbo Dodge 2.2 or 2.5 in there and use it as a shop truck. That plan requires time I haven't had so it just sits.

I can't remember if my Comanche has a carb or a throttle body setup. I'm pretty sure it's a throttle body. I can take a look, but I probably won't have time until tomorrow.

Thanks guys! Yeah, it's no powerhouse, but it's wicked better than the Hurricane flattie that came with it.

If it's all there and appears happy, I may try the throttle body set up. How bad can it be?

Dan

If you have the t-90 transmission in it already, you can get the Ford 4 cylinder adapter from Novak Adapters and then you can mount up a Kent/Lima/CVH/Zetec/SPI with a bellhousing from a 4 cylinder 4 speed pinto.

That's what I'd do; probably because I have the bell and a Zetec sitting in my garage already.

I had a '85 XJ w/ the AMC 2.5 and AX5, it worked pretty well w/ 3:73s and was kinda fun but in the end I still ended up wanting moar. As I researched back then, Clifford will prolly be the best engine performance bet. As with anything you can get crazy w/ them to where there is too much hair hangin' offa them for what hp gains you want then a engine swap may be in order like I did.

The 2.5 is a great engine... good power for the size, extremely reliable, and easy to work on. There arent many motors i like better for a small truck.

fasted58 wrote: I had a '85 XJ w/ the AMC 2.5 and AX5, it worked pretty well w/ 3:73s and was kinda fun but in the end I still ended up wanting moar.

The Fleetvan rearend is a 2.25 : 1. I see keeping up with traffic at highway speeds, off the line not so much.

Dan

Knowing Jeeps propensity for lots of gear, I think the 2.25 may be a miscalculation.

Lets see; one revolution of the tire and the yoke spins 2 1/4 turns. Holding one wheel and repeating, I get the same 2 1/4 turns.

Maybe it's not the stock one.

Film at 11:00 .....

914Driver wrote: Lets see; one revolution of the tire and the yoke spins 2 1/4 turns. Holding one wheel and repeating, I get the same 2 1/4 turns. Maybe it's not the stock one. Film at 11:00 .....

Don't belive that is the correct way.

Sure it is. Doesnt matter which side you input from, that just changes whether you call it 2.25:1 or 1:2.25. All you have to do is rearrange the numbers you get to make the diff ratio, but the numbers themselves are valid. As valid as eyeballing a driveshaft yoke can be, anyway.

914Driver wrote: Lets see; one revolution of the tire and the yoke spins 2 1/4 turns. Holding one wheel and repeating, I get the same 2 1/4 turns. Maybe it's not the stock one. Film at 11:00 .....

If its an open diff (or gov lock type) where one wheel is on the ground while you turn the other then you need to account for the spider gears. It sounds like you have an open diff based on the holding one stationary while turning the other.

For open diffs I leave one wheel on the ground and turn the raised one twenty times while counting driveshaft revolutions.

For example, 20 revs of the wheel make the driveshaft rotate 27 and 1/3 times would be 2.73:1

20 turns can be a pain, but It helps average out the error from eyeballing the percent of a turn.

Based on what you wrote it seems like you are closer to 4.50:1 (or whatever the closest actual ratio offer by the mfg is)

On edit: for limited slip (or spool) where both wheels have to be off the ground to rotate the wheel (and both go in the same direction), then counting the number of driveshaft rotations for 10 revs of the wheel is correct.

Joe

Far more accurate/easy to crawl under with both wheels in the air and turn the drive shaft.

Dan,

I finally had a chance to pop the hood on the Comanche and take a look. It's a throttle body setup. Should be the same as what you have now.

-Rob

Somewhere around 4.5 would be about right for what Jeep was running at the time. Heck, the CJ's were running 5.38 until the V6.

Thanks Rob. I'm going to keep the TB until I can't figure it out, then maybe go with a carb. As far as the gearing ratio; I can't change whatever it is.

Ok, drrp. I totally glossed over the part where he said he held one wheel still and got the same number. LOL