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Well when I'm not trying to figure out hoses to my charcoal canister I'm trying to hash out my next steps...which could include an engine rebuild. I've never rebuilt one but want to learn. Currently running an Iron Duke and would like a little more pop, so thinking the 4.0L MPI off an XJ or comparable might do the trick.
Well when I'm not trying to figure out hoses to my charcoal canister I'm trying to hash out my next steps...which could include an engine rebuild. I've never rebuilt one but want to learn. Currently running an Iron Duke and would like a little more pop, so thinking the 4.0L MPI off an XJ or comparable might do the trick.
4.0 is a good choice. Stick to a 91 to 95 4.0 if you can. Doesn't matter which vehicle. 96-98 should be good too but at some point they changed the block mounts on the 4.0 and they no longer worked with the cj mounts as a bolt on affair.
Try to get a donor harness from a 91-95 as well, they are much simpler to thin out and set up than the later obd2.
you have a 4 banger so you will need to use a 6 cylinder tranny. Since you have to go with a different tranny, if it were me, I would use the opportunity to avoid having to use the hesco CPS relocation kit. I am not sure what your knowledge is on the 4.0 injection system, but the CPS stands for Crank position sensor. It is a magnetic pic up that gets readings from the teeth in the 4.0 ring gear. The computer uses those readings in in the ignition system to cotnrol the coil and spark timing. The hesco kit runs about 400 bucks and replaces the balancer with one modded to work with the CPS.
Your other options are:
1. Use a AMC 258 i6 / 4.2l tranny with a 4.0 flexplate/flywheel and either mod the Bellhousing to mount the CPS
2. I think Advanced adapters has a BH that is already modified for the CPS
3. Use a 4.0 tranny nv3550/aw4/ax15 etc. The bellhousing already works with the CPS and you gain a hydraulic clutch system (This will require you to also swap in a YJ pedal assembly and MC) as well as a 5 speed tranny with good service strength
4. Buy the Hesco relocation kit and use any tranny you want
Other things to consider:
If you intend to run a mechanical fan, the XJ serpentine systems have the fan offset and would not be a good choice. You would need a ZJ or YJ serpentine setup. The brackets bolt on and off so you can still get the donor from a xj, yj, zj.
from what I have seen, the pre 91 4.0s used the the XJs are the same in the bottom end as the later 4.0s. So you may be able to get your donor motor from earlier xjs. If you do, however, you will need to get a head from a later motor (prefereably 91-95). The head and the injection system from the earlier 4.0s is considered a low out put version and not an ideal choice.
Someone else will have to chime in here but I think that a 4cyl TC will not bolt up to a 6cyl Transmission . It may be as simple as needing to change out the input shaft, but its something you should be tracking. If you are going with a 4.0 tranny you will need an adapter kit from AA to mate the TC which will come with a new input shaft.
ThisGuy - thanks for the information, super helpful.
I think a lot of the points you mentioned will take place after I actually rebuild this thing so I'll definitely keep them in mind. Based on those points it's clear that this isn't going to be a simple swap...I was hoping it might be more straightforward than that!
On the actual engine rebuild, sounds like I'm going to target a 91-95 4.0L and see if I can find a donor harness for it. Does the ECM generally come with, or is that something I need to specify from the previous owner?
While I'm in the rebuild process it sounds like I should also keep my eyes out for a new Transmission as well. I'll leave that topic for another day.
