With the miles adding up and the notoriously flimsy AX-5 tranny breaking for the second time, I decided to Go Large! After reading up on some six cylinder swaps others had done on the Internet, a nice stock 4.0L seemed right at the time. It turned out to be a pretty involved project with lots of surprises taking place over a five month period from Dec '04 to May '05.
To make a long story short and a more interesting read; I rebuilt a junkyard block, mated a much more sturdy AX-15 to it and rebuilt the NP231 T-case to go with the new tranny. Sounds easy, huh? I forgot to mention the wiring harness, new computer and exhaust. And, let's not forget having to cut off and weld the motor mounts a few inches farther up the frame.
The difference between the 2.5L and the 4.0L was like night and day! No more shifting gears on the interstate!
After running the 4.0L for a few months, I began reading some of the posts on the strokers forum and started acquiring parts for my next project, the 4.6L. I ran the 4.0L for a grand total of eight months. Pity and a waste, but I $old it to a fellow Jeeper with a CJ.
The build wasn't as hard this time, it was just a simple swap. I've robbed quite a few graves to bring this Frankenstein to life and that was/is the beauty of AMC/Jeep. They saw a good thing in the straight six way back then and stuck to it until 2006. Anyway here is the parts list, year, sources and prices when I can remember. It may help somebody out there that has a YJ.
Vehicle:'93 YJ, three inch lift, 32." All Terrain.
Engine block: junkyard '91 bored .030" over and decked .020".
Tranny:'90 AX-15 from an XJ-yes, the rear is different. Modified the t-case linkage and made 1inch bushings to set the drive line angle.
Head: '98 0630 casting, ported and polished, drilled and tapped for the YJ's temp sending unit. Modified cast valve cover. Oh yeah, you have to saw the bottom off!
Crank and rods: out of a very old 1970ish International Harvester pickup truck that had the mighty fine AMC 258.
Pistons: 24cc 2229's
Intake manifold: '01 YJ with the corresponding '01 P/S pump and weird belt routing.
Exhaust: stock header with home brew 2.25" pipes and Flowmaster Super 40 with Carsound high flow cat. Very obnoxious to everyone but me.
