4.0L in a cj7

i want to put a 4.0L form a 97 xj in to my 79/78 cj7 with a t-150 tranny will i need an adapter kit or will it bolt right up can anyone help me with this one

thanx mike

 

i thought so but wasnt sure thanx

 

Same bellhousing bolt pattern, but you will need to have the bellhousing machined for a crankshaft position sensor if you are going to use the factory fuel injection.

 

I put a 91 Xj motor in my 83 cj7 years ago. I wouldn't trade it for anything, the power and reliability is amazing.
There are some tricks though.

The motor mounts off the 258 will bolt to the 4.o, but you will have to tap threads and they are a metric thread if you want it to match the other holes.
The Xj uses an offset mechanical fan and a electrical fan. The water pump snout willnot allow you to put a mech fan on it. You will need to get a YJ pump.
I used the Mopar kit wiring harness, dist (1995) fuel pump, computer and air intake components that I got thru Hesco, who apparenly put the kit together. They also had the harmonic balancer and bracket to put the CPS on the front instead of on the belhousing (highly recommended). I also adapted the delco alternator by modifying the stock alt brackets. I had to put a diode in one of the alt wires so the engine would shut off. I mounted the pump on the frame rail (it makes a noticable hum but I live with it) and used a low pressure filter before it and mounted the stock hi pressure filter and bracket off the XJ on the pass inner fender, and ran the lines under the motor and up to the hookups on the intake manifold. I used the stock exhaust manifold (which has now cracked very common) and ran stock type exhaust with a welded in bung for the o2 sensor, I think some later manifolds have a machined in boss.
I think if I was in your shoes I would try to identify if the various sensors on the motor will interchange with a 95 model year, and if not change them to a 95, which is what the mopar kit is based on. This would allow you to use the mopar kit computer and harness which while maybe a little costly would make things easier in the long run. I got my motor for free and spent almost 1000 on mopar kit components, exhaust, and various other misc before it was done. All worth it though. I am in the field right now so no pics, but will be back in about a week and a half. Any other specifics you have questions on feel free to ask.

 

im going to try and use the harness and computer out of the xj and the reason i want to go with a 97 is cause thats when they chenged to obdII and it gets better fule milageif i wanted to spend 1000 on the mopar kit than i might as well keep the 258 in it and just buy the fule injection kit, as far as wiring goes i probly can rig something up im on a tight budget so i have to make due with what ever i can get my hands on.

is there a reason i cant use the harness out of the xj??
and i didnt even think about the fan issue what about using 2 eltric fans??

thanx mike

 

Mmm... I think the Mopar MPI kit is up to about $2K now. The Howell TBI kit is $1K.

Plenty of motivation to use the XJ parts...

The page about putting the SM420 behind the AMC 150 has some good crank sensor pics. I think if you're handy you could put the sensor at the stock location (on the flywheel). http://www.jeeptech.com/wiki/index.php/Transmission/Conversion/SM420/Swapping_a_SM420_into_a_YJ
Novak also has a picture of this http://www.novak-adapt.com/knowledge/465_to_amc.htm

 

If you allready have a 258 it would be the closest "bolt in" engine swap you could do. For info on the different fuel injection systems I would find the yahoo strokers mailing list. Very knowledgable people on all the different fuel injection systems out there for the 4.0. Definately worth checking out.

Oh, and if you don't want to do the relocated cps on the harmonic balancer you can allways send your bellhousing to Novak and they can machine it for a stock cps mount. I think they charged me $65 to do it.

Kevo

 

I am pretty handy with wiring and auto electronics, and the 91 XJ harness intimidated me. IIRC the engine harness and various body and gauges harness were altogether in one, and looked like a bear to separate and lengthen and shorten wires to make it neat etc... it was a days work to get it running using the kit pieces. I got my motor for free with less than 1000 miles on a complete rebuild (truck rolled end over end 2 or 3 times). I have heard issues of the 258 running lean using the kit, I liked the idea of swapping in the whole motor. Fan choice is up to you, I like mech fans for reliability and simplicity.
As for the CPS, I paid to have my bellhousing modified and it did not work, although the whole thing had some other issues at the time (long story). In case you did not know, the CPS on the earlier 4.0s are a common culprit to go bad and cause starting/running problems. I like the idea of having it on the front of the motor where it is easy to put the spare on if it ever fails on the trail (yes I do carry a spare, I also carry a spare pump).
If it was me, I would still look at using the kit harness, and one could scavange all the various sensors, dist, and computer from a junk 95 4.0, and fab the air intake stuff.