4.2 to 4.0 swap

My 1990 YJ when it still had the 4.2

When i got my yj wrangler a couple of years ago, i noticed it had a carbureted motor in it and I didn't really think much of it because I thought it would be a good motor since it was a six cylinder.  After driving it a while, i realized I was wrong.  It leaked and burned a lot of oil, about 1-2 quarts per week.  It also wasn't very powerful, and it had bad gas mileage, which was around 10 mpg.  After driving it for about a year with that motor, i decided i should try to find a motor to swap into my jeep.  At first,  I wanted to just try to put a head from a 4.0 on my motor which would give it about 30-50 more horsepower, but i wanted to go with fuel injection.  Then, I wanted to put a 5.3 Liter V8 out of a 1999-up chevy truck, but after some shopping, i realized that would be over 1500 dollars, plus having to deal with the axles breaking over time and having to change the motor and transmission mounts.

After doing a bunch of research online, i realized a 4.0 out of a cherokee or a newer (91-95) wrangler would bolt right in and would need minor wiring modification.  So, i tried to find a cherokee motor, but it was hard to find one that wasnt parted out already.  Since i was going from carburetor from fuel injection, i would need the fuel lines and gas tank from the donor vehicle.  After doing some searching, i found out that a junkyard near where I live had just gotten a 1994 wrangler with a 4.0 and a manual transmission, which is really nice because if I were to get one that was bolted up to an auto, i would have to get a new computer for the manual transmission.  So, i decided to get the one from the wrangler.

In future posts on this blog, i am going to describe the steps i had to go through to get the new 4.0 liter motor to work in my wrangler with the 4.2.