What do I need to change from a 4 to 6 cylinder in a YJ?

Speed Freak

Member
Joined
Jun 28, 2005
Location
High Point
If I buy a running XJ with an automatic transmission what other parts will I need to convert my 94 YJ to a 6 cylinder? I would also like to use the automatic trans instead in my 5 speed. What will I need to do that?
Thanks
Guy
 
your going to need new motor mounts to start with. you didn't say what year XJ you were buying but the close to 94 the better. when I did it, i wound up having to get a 6cyl wiring harness for a YJ to get it all to work right. you can do it by meshing the two wiring harnesses but it will be easier to get a wiring harness from a 4.0 wrangler. your radiator will work as they have the same one. You need to get the motor mounts exactly right, that's the hardest part. good luck!
 
Do I just buy 6 cyl. motor mounts from NAPA or do I have to make my own? What parts of the harnes do I have to mesh, just the dash and gauges?

What about the automatic? Will it bolt right up to the trandfercase?
 
Make sure you get the computer. Check fuel pressure requirements because the fuel pump for the 4 cylinder may or may not give enough pressure for the 6 cylinder. I have found a lot of good info at
http://www.novak-adapt.com/index.htm
When I did my swap. I replaced my YJ 4 cylinder with a Chevy 4.3 Vortec.
 
The motor mounts are completely in a different place, so you need to buy conversion mounts that bolt in or weld in or fab you’re own if you have the ability. The wiring differences are many and its simplest to use the donor engine harness, dash harness and computer, and transmission harness if it has one all from the same vehicle preferably a YJ of the same year as your YJ. If not things just get difficult such as the fuel pump wiring may be in the engine harness or the dash harness and that’s just one critical connection you may have to track down and wire in on you’re own.
 
Break down of my swap

-Remove Grill
-Remove both finders + wiring + etc etc
-pull motor yada yada yada
-pull harnesses and comp.
-Grind welds
-Move motor mounts up 6" (tack weld and put in motor to check) weld down
-put finders back on
-put grill in
-put in new comp and harness
-put motor in

I found that converting a man. to auto is quite difficult
you will have to remove the clutch assly. Also you will have to figure out how to bypass the safety kill switch. But keep in mind my swap was man to man.
 
You'll need the xfercase from the 4.0 rig also. Yours behind an AX5 is a 21 spline input, the ones behind the 4.0 auto and AX15 are 23 spline.
 
Contact Lee on here. He put a 4.0 and auto from an XJ into his YJ. He is now putting a v8 in and looking to sell his complete set up. Sounds like it would work for you.
 
Back
Top