Swap a MFI AMC 2.5 into a Spirit with iron duke?

If you use the last model Jeep 2.5L EFI system it will be more power than the carbed Iron Duke, less than a 4.0L. But you also get a lot better drivability and it will almost bolt in. The mounts are slightly different, but I haven't had them side by side to compare. Look the parts up on some Jeep sites -- the Iron Duke was used in CJs and the early AMC/Jeep 2.5L with carb was too.

Keep in mind that the AMC/Jeep 2.5L uses a 60 degree Chevy V-6/I-4 bolt pattern though. The Iron Duke used a SBC pattern up to 1982, 83 and later use the smaller V-6/I-4 pattern. 83 models used in CJs and Concord/Spirit may still have the SBC pattern, but 84+ Jeeps (and 96-02 Dakota pickups) use the small pattern. So you will have to change transmissions.

1983 AMC Spirit w/Pontiac 2.5L - 82 hp @ 3800, 125 ft/lbs @ 2600 rpm

1996 Jeep Wrangler w/AMC 2.5L - 116hp @ 5200 rpm, 137 ft/lbs @ 3600 rpm

Power seems like a lot more, but look at the rpm data. I'm really surprised that the AMC engine turns that much more, since it has a slightly longer stroke and smaller bore (stroke is 0.20" longer -- just under 1/4"). So there will be a drivability improvement, but not a lot more power. A bit of a mileage improvement also, due to the greater efficiency of EFI. Might be getting back to "is this a worthwhile swap" though. If the 2.5L Poncho is well worn and you have access to an inexpensive AMC 2.5L and (RWD) trans, sure. Otherwise, you're not getting a whole lot for the effort. A 4.0L will be more effort and cost, but a much bigger improvement in power at about the same gas mileage as the carbed 2.5L Poncho.

Chrysler had come out with a new four cylinder family in 94 for their FWD cars, and dropped production of the older 2.5L. They stated at the time that the AMC four was more suitable for a truck than the new 2.4L, but the specs are nearly the same, with the 2.4L Chrysler having a bit longer stroke. The new engine was optimized for FWD though, and may have used a different trans bolt pattern, so using the RWD configured AMC engine made more economical sense -- either that or drop the AMC engine for the Chrysler. If the Chrysler engine could have economically been easily used in a RWD configuration I think dropping the AMC would have been the wise choice, unless there wasn't enough production capacity to build enough of the new engines for cars (and mini vans) and trucks.

Again, your market may vary. I guess all I'm saying is a cherokee 4.0 is more common, 4.2 engine mounts work, and you're only left figuring aw4/ax15 trans mounts (also given MY OPINION), since most other options don't offer longevity

To me, all things equal, the Chrysler 2.5 turbo is a much more interesting 4 banger swap, but the obvious problem of that engine was offered as a fwd engine, and what trans would someone mate to it for a rwd application. Knowing that in chev bodies, the 2.2 ecotec (an amazing tuner engine IMO ) has been stuffed into s10 trucks, I would hope there may be an available option

As a side note, personally i,n the new Era and considering evolution and keeping amc bodies relevant, I find this discussion very interesting