Has any body replaced a 258 with a 4.0L or seen an article on it? I'm trying to find out how much trouble and money it would be.  

        The only thing I wouldn't bet the farm on is, the bellhousing, but something makes me think it will bolt up. Motor mounts, hose, in & out, should all be the same from 4.0 to 4.2. The hard part will be the wires, fuel lines, reworking the fuel tank, and such, if you want to keep the EFI. If you have a good doaner Jeep you can lift parts from will be the way to go, and if thats the case use the trany thats hanging on the 4.0 now, later model 4.0 have the trans all wired up with the ECM, and you would have to use it anyway. No matter how to want to look at it, its going to cost you a few bucks, and hours of pulling wires. But it should bolt right in. I don't know how you are planing to use it, but I looked in to this myself a while back. I ended up having my 258 rebuilt, and converted it to EFI, with the kit from Howell. It solved all the problems with the 4.2 you must know about. Total cost for this set-up, with a complete rebuild of the engine, .030 over, forged pistons, ( good idea with a long stroke engine, keeps the slop out of the wrist pins ) and the EFI set was about $3200. Worth every cent. You could end up spending that and then some, by the time you get everything you need together, and you still end up with a used engine. Thats how I justified it. Still don't think the old lady is buying it, LOL. You won't end up with the same top end power to 4.0 will make, but the EFI on the 4.2 makes gobbs of low end pull under 2000 rpm, and much better drivablity, over 2000 rpm. The power band does not peak out so fast as they did with the carbs., and leave you needing more pull after 1800 rpm. Well, thats about 5 dollars worth of my 2 cents, best of luck, any questions, feel free to ask.  

Thank you for your answer. You sound like you were going through the same thought process I am. I had hoped to find the swap easy but I kind of figured on a lot of work, my luck. I agree with you about new vs. used engine especially when the EFI was my main target any way. I never used to mind the hassel of carburation but the older I get the less I want to fiddle with it. As for justifying the cost of the rebuild, I figure thats about 5 new truck payments after that it's just gas and oil again. Thanks again Hook.  

    If you didn't know, Mopar also makes a kit for the 4.2, to conv. to a port injected, EFI, with the damper- trigger, about 3000 grand alone. I also have herd stories of close to 300 ponies from your 258, if you cam it right, with this set up. Have also seen some good runners with the Weber carbs. too. Also an FYI, if you have that same pile of steaming Carter carb I had, the over rich, or that lip home deal the ECM goes into will dump so much fuel in your engine, it washs the oil off your rings and wrist-pins. Mine started knocking at just over 100,000 miles. That was the problem, "FUEL WASH". Buddy of mine that has worked in a Jeep dealership for 20 plus years said they would get a lot of warnty jobs for this problem on the 87-90 YJ's. Would see the same prolem on the last few years of the CJ, 82-86. Just wanted you to know there is more to it than just running like crap. Again, good luck, and speak up if'n ya got any questions.  

Thanks Paul. Your full of great info! I got rid of the carter and all the electronics that went with (don't tell EPA) but the fix hasn't proven to be a lot better. I put on a holley 2150, sometimes it works like a champ sometimes a chump. The 2150 is unlike most holleys and I'm not sure it's set up right. It's probably going to take a trip to a pro to get it sorted out. My engine is closing in 100k so the planning continues for the inevitable replacement. I'm not real power hungry so the rebuild will probably be tame except a low end cam and EFI. If I run into any snags I'll look you up. Thanks again Hook.  

I just completed this very swap on my 86 CJ-7. Pretty much a no-brainer. If you have halfway decent mechanical skills it should be a cinch. It's a direct bolt in - bellhousing on my T-5 bolted right up (although I swapped in a World Class unit) and I utilized the motor mounts from the 258. I had the flywheel resurfaced and used it again. I ordered the pilot bushing from Advanced Adapters (an absolute fantastic resource for the swap as far as technical help). Forget trying to use the original harness though - it's a nightmare. Do yourself a favor and get a loom from Hesco. It's a direct plug in, and I had it wired up in no time. When you remove the original unneeded wiring from the CJ (all you'll be saving is headlight and ignition wiring) you'll be amazed at how clean everything is. Hesco will even sell you the required external fuel pump (I mounted mine on the frame rail next  to the tank) and speedo sensor. You'll also need a damper/crank sensor to make the thing run - also available from Hesco or Advanced. Total for the wiring loom, sensors, etc., was about 700 - 800 bucks. Not cheap, but if you get a engine for a decent price (I got a new 4.0 with less than 800 miles) it beats a rebuild. The hardest part was probably running the fuel lines, but I'm pretty anal about the work I do and I took my time. Plus, I had the body off of the frame so it made it that much easier. The darn thing started on the first turn of the key and ran like a champ! Biggest thing to look for - make sure the computer from the donor vehicle is compatible (an automatic ecm will not work with a manual tranny). If you need some help shoot me an email and I'll be more than happy to help if needed.  

Very cool, and some good info.

I got myself a '99 4.0 with the computer and harnesses for $700 canadian (about 50,000 miles).  I sold the computer and harnesses for $250 .... so my total cost was $450 plus bit's and pieces.  It had all the accessories.  It went into my '97 TJ ... so my only point is that good, cheap engines are around.  Also, i have some great spare parts.

Chrysler wanted HUGE $$$ to even look at my jeep.  It took me a while, but i got it going.  

pete