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  • engine swap

    alright, seems this is the new topic of choice around here, but nothing spacific enough for my situation, so here i ask. i have a 85 cj-7 4.2 258. anda 5speed trany (what number is this t-???)
    the salvage yard has a cherokee that had 2,000 miles on it and the owner rolled it. it has a 4.o 258 with the fuel injected throttle body. and im asuming with a auto tranny. can i swap this in with my original transmition? and how hard would it be? ive never done a engine swap before, but my dad has and he will be helping me. what are some of the hidden expenses i need to know of? thanks

    (i dont plan on doing this right away, im just exploring my options. the salvage yard is asking only 400 for the engine)

  • #2
    Your transmission is likely a t-5... but could possibly be others i think.

    The swap isn't too bad as far as swaps go... but it's not as easy as 305-350 chevy swap or anything like that.

    The 4.0 does bolt up to the t5 bellhousing.

    This is certainly not a complete list of issues:
    1. I 'think' youll need a new flywheel... might luck out and reuse original.
    2. I'm pretty darn sure you'll need a new pilot bushing, possibly custom.
    3. Make absolutely sure you get the wiring harness and all associated gadgetry and sensors... heck just buy the whole cherokee til you're done with it.
    4. Depending on how you do it, you'll either need to hack up your bellhousing for the crankshaft pickup sensor, or buy the setup from Hesco.
    5. don't forget the hidden cost of about 12 cases of your favorite drink.
    6. plugging the 4.0 harness into the cj requires figuring out which 4 or 5 wires need to be spliced in, and where they need to be spliced in at.
    7. The exhaust is slightly different (down tube?) so figure 50 bucks or so for a muffler shop... or about 2-3 hours of fabbing up your own.
    8. If fuel injectors are leaking... replace them, figure 10 bucks a piece used.
    9. a bucketful of patience.

    good luck. There are write-ups on the net, try google maybe? Kinda have to piece together 4.0 head swap writeups with other writeups, but the info you'll need is out there.


    • #3
      OH, how'd i forget?

      Fuel pump (maybe even 2 to prevent air in the lines or some such?), fuel filter, new flexible gas lines for the increased pressure of FI.

      Electric fan... because the cherokees have an offset mechanical fan and a tiny electrical fan. Oh and you'll need some type of fan control also... or you can get by with the stock cherokee one and some relays.


      • #4
        I was just reading an article on that today. I like to read alot of stuff during my planning period, but the site is on my computer at school- I'll put it on here tomorrow. It has the wire colors cited to match the harness with some of that Hesco stuff listed previously. There is a bunch of stuff out there- type in "4.0 CJ swap" on a search engine and go. My newest idea is that if I'm gonna put in a 4.0 for the convenience of fuel injection, may as well make it a 4.7 stroker first. I still think that doing all of that is far lest costly than dropping in a chevy. Hopefully, someone who has done this will toss in their $.02.


        • #5
          if the cherokee has a 4.0 FI it's most likely a later model than your CJ. if thats the case, it's a DC jeep, not AMC. if that's the case, it's probably not going to bolt up w/o an adaptor. give us a little more info as to the specifics of the cherokee (xj i assume).