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Discussion Starter #1 (Edited)
I've never seen the TJ 4 cylinders mentioned as swap candidates. They're readily available and although underpowered for a TJ, it seems like a decent match on paper for one of the 40-50s models.

I'm finishing up a TJ frame swap/ rebuild currently, but I would love to do a Willy's build next. My uncle has a 53 cj3b just rotting away in a field that I could scavange for parts. The tub is very rough, and the tailgate isn't too great, but the hood, grill, and windshield all still look decent. It was running when parked, but I don't think I would be using any of the drivetrain anyway.
 

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personally, I wouldn't mess with any motor that needs a computer and all them wires. Better yet, any motor that needs spark plugs :flipoff2:

The 4cyl TJ motor should be plenty of power for an old willys though. I know folks who wheel some pretty hardcore crawlers with TJ 4cyl motors. Gear it right, and it's just fine.
 

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I have a Tj 2.5 and run 35" MTZ's. It is geared to 4.88. But my Tj will run 60mph anywhere in the mtns of Wv. In a Willys that weighs 1000lbs less it should be a great combo.
 

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According to wikipedia:
Flat head: 60hp, 105ft-lbs
2.5l: 130hp, 150ft-lbs,
2.4l: 147hp/165lb-ft

So either of the newer 4-bangers put out a fair bit more power, and I would care to venture are lighter to boot. If you keep the rig light I dont think they are a bad choice, of course I may be a bit partial............


I am stuffing the whole 2.5l/ax-5/np-231 combo from a YJ into mine. Sure its no powerhouse but if you focus on keeping the build light and gear the axles low (they had 4.10's with stock tires) they get the job done.
 

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I have a friend that started the same project about 8/10 yrs. ago. looks to be about the same stage your in. A new kid and the project had to go to the back burner. He picked up the complete package for $600.00 all still assembled. Like you said and we talked about, in a light package it should be a good combo. Keep up on the build I'm interested to see how it comes out.
 

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Discussion Starter #6
Thanks for the replies. I'm still in the early stages of considering this. I'm wanting to take a summer welding/Fab course next year which will require me to quit my current job, so if I end up doing that I will be too short on cash. Otherwise, I think I can get quite a bit done on a $5000 budget or so, which is why I am looking at a cheaper alternative like the TJ 4 cylinders.
 

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I think a donor vehicle would give you the biggest bang for the buck. With my build I have reused the engine/trans/tcase, front axle, steering gearbox, steering linkages, pedal assembly, brake booster wire harness etc etc. I probably only been able to sell the jeep for $800-1000 (ran great, looked bad) you can't buy all those parts separately for that price! An XJ would be a good donor too as they are mechanically the same and they are cheap and plentiful.
 

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Discussion Starter #8
I think a donor vehicle would give you the biggest bang for the buck. With my build I have reused the engine/trans/tcase, front axle, steering gearbox, steering linkages, pedal assembly, brake booster wire harness etc etc. I probably only been able to sell the jeep for $800-1000 (ran great, looked bad) you can't buy all those parts separately for that price! An XJ would be a good donor too as they are mechanically the same and they are cheap and plentiful.
That may be be a good idea if I could find a 4 cylinder xj cheap that wasn't also completely ragged out. I would need all the wiring and stuff, and an HP 30 front would be a swap candidate also.
 

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Discussion Starter #10
The 2.4 engine is much better than the 2.5 fwiw.
Yeah it is, but I'm assuming it's harder to find by quite a bit, and the price would reflect that.

Any opinion on the manual transmission options? The six speed offered with the 2.4 has a lower first gear than the 5 speed that came with the 2.5. I'm assuming both auto transmissions may be a little too long for the build, although I would likely stretch the wheelbase back and run a fuel cell.
 

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Speaking of transmissions, I remember a magazine article about 20 years ago that showed the SM420 being almost a direct bolt up to a 2.5 bell housing and that is perfect for a drivers side diff since the huge SM420 hump is on the passenger side.
 

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Speaking of transmissions, I remember a magazine article about 20 years ago that showed the SM420 being almost a direct bolt up to a 2.5 bell housing and that is perfect for a drivers side diff since the huge SM420 hump is on the passenger side.
I think you need an S10 bellhousing to make that work.

The really early 'iron duke' 2.5s in the CJs with the GM bellhousing pattern can just use a GM bellhousing.

Tri-county Gear still makes an inertia ring for the flywheel that is suppose to help with low end performance a LOT.
 

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I think you need an S10 bellhousing to make that work.

The really early 'iron duke' 2.5s in the CJs with the GM bellhousing pattern can just use a GM bellhousing.

Tri-county Gear still makes an inertia ring for the flywheel that is suppose to help with low end performance a LOT.
Dakota or xj. Somewhere I have one. You have to cut it for the CPS.
 

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I think you need an S10 bellhousing to make that work.

The really early 'iron duke' 2.5s in the CJs with the GM bellhousing pattern can just use a GM bellhousing.

Tri-county Gear still makes an inertia ring for the flywheel that is suppose to help with low end performance a LOT.
Dakota or xj. Somewhere I have one. You have to cut it for the CPS.

Yeah, it was a YJ 2.5 in the article...I knew you guys would know the details.

:beer:
 

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Do those have the right transmission pattern? Or would those be the ax-5 type stuff?
I don't recall. Been too many years. Widej was the one that told me about it.
 

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I got all excited about the sm420 swap thinking that it would be a great plan B if my rear drive shaft ends up too short with the AX-5 trans i am using right up until i found this: "The overall length of the trans is shorter than the stock combo, the rear driveline can be lengthened about 3/4" "
Swapping a SM420 into a Wrangler

Can that be true? I thought the AX-5 looked rather long, but maybe its not as bad as I thought...........
 

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I got all excited about the sm420 swap thinking that it would be a great plan B if my rear drive shaft ends up too short with the AX-5 trans i am using right up until i found this: "The overall length of the trans is shorter than the stock combo, the rear driveline can be lengthened about 3/4" "
Swapping a SM420 into a Wrangler

Can that be true? I thought the AX-5 looked rather long, but maybe its not as bad as I thought...........
SM420 should be 13.9" adapted plus 6.5" for the bellhousing for a total length of about 20.4"

The AX-5 is 15.63" plus 6.5-7.5 for the bellhousing for a total length of 22.13-23.13" long.

So it looks like it should be over 2" shorter.
 

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If you can find a Dakota 2.5L 4cyl bell housing it allows you to run an AX15. Which is a WAY stronger trans. Then it's simple to swap a Dana 300 to the AX15.

I have an inertia ring downstairs for my 2.5, I just haven't installed it yet.

Also AA makes a kit to bolt a Np435 to the AX5 bell housing. But you gotta swap input shafts. And you'd have to buy an adapter to run a decent case...but it would be nice to have the lower 1st gear option..
 
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