Thread: Plymouth with the heart of a Jeep

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I'm about to begin an engine swap for my '38 Plymouth sedan. Being someone who likes something a little different, I've decided on the amazing 4.0 High Output Jeep six and the matching 4 speed overdrive Jeep automatic. My donor is a ‘91 Cherokee with only 65K on the clock prior to going into a ditch and messing up the bodywork. I plan to use the EFI with the computer and all. The car will get a complete rewire and 12 volt conversion. I’ll also will be adding an air/heat/defrost unit from Airtique and hope to swap in the Jeep 20 gallon gas tank as well. Just wondering if anyone has any experience with this or a similar swap. I expect quite an adventure since I've never swapped in a brain before. Any advice would be appreciated.

No experience with the swap but glad you aren't using the 89 or 90 Jeep 4.0 HO motor. Those two years had the interim French electronics. Complete waste of a good car.

I like what you propose there. I have had a bunch of the Jeep 4.0 XJ Cherokees and they get up and haul ass for a 4800 lb rig. Stone dependable too with regular maintenance.

I went just the opposite route.......I pulled the 4.0 out of my Jeep Commanche and swapped in a 5.0 Ford. But I only did that because the Jeep engine had a bazillion miles on it and the tranny died. You are right, these are very solid, dependable engines, and have been so for many years.

Ok, here is my advice. I would make sure the 4.0 runs well BEFORE you turn a wrench. You mention it is wrecked, but how bad? Does is start and run? If it does, get it running and if it isn't too badly damaged, try to drive it. You want to make sure all the systems are working well before you swap it in, otherwise you may come up with some running issue, and not know if it was something you did in the swap or if it came aboard that way.

Then, you want to take very detailed pictures (lots and lots of pictures) of every little wire hook up and hose, and bracket, and........... Also make detailed drawings of these areas, and make more as you take stuff off. Bag and label every part that comes off.

Try to disturb as little as possible, especially components that are affixed to the engine. What you are trying to do is not create any problems for yourself, by not hooking up some component that the computer may read as a fault.

Remove the computer and associated wiring and hoses in as much of a bundle as possible, and find a suitable mounting place for all of this stuff. Computerized cars are not my forte', and I do not understand all the stuff that goes with them, but I do know that items you may deem unimportant may play some role in making them function properly.

Get yourself a detailed wiring diagram for the 4.0 donor, what you are trying to do is turn the Plymouth into the Jeep. Take every little bracket, hose, etc off the Jeep and remount it on the Mopar.

I can't speak to the clearance issues you will encounter, as these will follow normal hot rod engine swapping procedures. But your new engine will have sensors and switches that you can't imagine, and they all play a role in the proper operation of the engine.

I think it will make you a very cool driver when done. Good luck.

Don

Thanks for the positive feedback, guys. When the donor Jeep went into the ditch, it only hurt the sheet metal. It still drives just fine and I'm checking all the electronics prior to dismantling to make certain there's no problems. I plan to take it slow and be as thorough as possible with lots of photos, digital cameras have sure made that part easier. I've even put a computer terminal in my shop so that I have all those pictures handy for review as I go. I also have a '92 Cherokee (my daily driver) so I can refer to an intact operating system when needed.
Cuff