GrayWolf1691 Posted March 6, 2019 Share Posted March 6, 2019 I recently got my Jeep back after parting with it 4 years ago. In that time the ol 2.5's rings have started giving up. My cheapest option is to obviously put another 2.5 back into it. I have an ax-4 transmission. I had played with putting a 4.0 in but currently that is an option that will have to wait. But I was told with an OBD 1 4.0 you could use the intake manifold from an old 4.2 to convert it to carb. So I was wondering if I'd be able to get away with an OBD 1 crate 2.5 and be able to swap the intake manifold and if the knock sensor mounting would be the same and if motor mounts are the same. The shop I asked for quotes is trying to tell me I'm looking at $10k to do a 4.0 swap which seems excessive. Hell, I'd be happy if I could get by carbing an OBD 1 2.5 for the time being. If someone is able to help I'd really appreciate it. I'm at a loss how to proceed with it. Link to comment Share on other sites More sharing options...
Lthompson741 Posted March 6, 2019 Share Posted March 6, 2019 10K for a 4.0? Damn!! You could buy a entire XJ and swap everything you need over multiple time for 10K. Look into a donor XJ to swap over. Link to comment Share on other sites More sharing options...
Pete M Posted March 6, 2019 Share Posted March 6, 2019 what are your compression readings? Link to comment Share on other sites More sharing options...
yxmj Posted March 6, 2019 Share Posted March 6, 2019 I will swap it for you for $9500.....that includes the engine and me travelling there...... Link to comment Share on other sites More sharing options...
GrayWolf1691 Posted March 6, 2019 Author Share Posted March 6, 2019 Compression readings 4 years ago were about 130 across the board. I moved to Washington a bit north of Seattle, traveled to Eugene, Oregon to get it. Oil blows out the dipstick tube and coated the front of my car in oil that a buddy was driving back for me. Fair amount of spitting and sputtering but it made the drive. I appreciate the offer but I have a neighbor that would do it for cheaper. Link to comment Share on other sites More sharing options...
Eagle Posted March 6, 2019 Share Posted March 6, 2019 14 minutes ago, GrayWolf1691 said: I recently got my Jeep back after parting with it 4 years ago. In that time the ol 2.5's rings have started giving up. My cheapest option is to obviously put another 2.5 back into it. I have an ax-4 transmission. I had played with putting a 4.0 in but currently that is an option that will have to wait. But I was told with an OBD 1 4.0 you could use the intake manifold from an old 4.2 to convert it to carb. So I was wondering if I'd be able to get away with an OBD 1 crate 2.5 and be able to swap the intake manifold and if the knock sensor mounting would be the same and if motor mounts are the same. The shop I asked for quotes is trying to tell me I'm looking at $10k to do a 4.0 swap which seems excessive. Hell, I'd be happy if I could get by carbing an OBD 1 2.5 for the time being. If someone is able to help I'd really appreciate it. I'm at a loss how to proceed with it. That shop's price for doing a 4.0L swap seems incredibly excessive even if their price includes completely rebuilding the 4.0L engine. But that wasn't your question. The Comanche came out in 1986, with throttle body injection. But AMC Jeep used the exact same engine in the Cherokee in the 1984 and 1985 model years with a carburetor. It was a crappy carburetor, to be sure, but it was a carburetor so you should be able to source an intake manifold from a junkyard. The question is, what carburetor would you use? Some years ago, a lot of Cherokee 2.5L owners seemed to like a Weber carburetor, but I don't recall the exact model. Link to comment Share on other sites More sharing options...
Pete M Posted March 6, 2019 Share Posted March 6, 2019 I would do another compression check and a leakdown test before going to far down this path. but anywho, ANY 84+ 2.5L block will go right in. doesn't have to be an old one or even from an MJ/XJ. wrangler stuff works too. can't remember when they last used it though. 2002? Link to comment Share on other sites More sharing options...
GrayWolf1691 Posted March 6, 2019 Author Share Posted March 6, 2019 My neighbor does have a 98 2.5, I haven't had time to talk to him about it. If he has the wiring and ecm and stuff and it'll drop right in I can deal with wiring on my own time. If mounts aren't an issue then that solves 80% of my problem. Thanks Pete. Link to comment Share on other sites More sharing options...
dasbulliwagen Posted March 6, 2019 Share Posted March 6, 2019 Assuming the only issues with the current 2.5 are low compression and bad blowby, why would you convert to carb??? Is it just to make a carb version of the 4.0 easier to do later? I believe the shop quote was mostly labor time as I could see the cost rising quickly for the amount of time it would take to strip down an XJ carefully saving the harness then stripping down your MJ to have that harness installed and then the engine and trans on top of that, not to mention the driveshaft. I could see it costing$10,000 in that case. That and I'm sure that number is an "I don't want to do that job" number and they'll only do it if it is really worth their while. Link to comment Share on other sites More sharing options...
GrayWolf1691 Posted March 6, 2019 Author Share Posted March 6, 2019 The carb would play two purposes, 1) I wouldn't have to deal with wiring 2) I like fiddling with tuning every once in a while Otherwise there really isn't a reason. My family always had Chevrolet and whenever we ended up with something throttle body injected if something stopped working my dad and brother just tossed a carb on it. I've just been trying to figure out the least labor intensive option available since I don't have a lot of time on my hands. Link to comment Share on other sites More sharing options...
Eagle Posted March 6, 2019 Share Posted March 6, 2019 8 hours ago, GrayWolf1691 said: I've just been trying to figure out the least labor intensive option available since I don't have a lot of time on my hands. The least labor intensive option available (which is pretty redneck) would be to drop the pan and pull the head, remove the pistons, re-hone the bores, put new rings on the pistons and new rod and main bearings, and slap the head back on it. A friend of mine has a Wrangler 2.5L that blew a piston last year (he plows snow with it, and may have worked it a bit too hard). He bought a set of pistons, put rings on them with new rod bearings, didn't touch the main bearings, and buttoned it up. Runs better than it ever did. Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 7, 2019 Share Posted March 7, 2019 You might want to rethink your approach. Link to comment Share on other sites More sharing options...
Eagle Posted March 7, 2019 Share Posted March 7, 2019 1 hour ago, Jeep Driver said: You might want to rethink your approach. To whom was this addressed? Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 7, 2019 Share Posted March 7, 2019 19 minutes ago, Eagle said: To whom was this addressed? To the OP. There is no knock sensor on the 2.5..........OBD1 or not. There is no such thing as an OBD1 "crate" 2.5 And I have no idea why he is chasing a carb scenario............... And for that matter, if he was to go carbed he'd be better off using a MPI intake........2 bbl adapter would work out great, he'd have to make one of course. He did not mention but what? OBD1 ignition? .......TPS adapter to carb?...........IDK? Aftermarket ignition? '84 points distributor? what? Link to comment Share on other sites More sharing options...
kansashogan Posted March 7, 2019 Share Posted March 7, 2019 I would agree with Pete on this. Cheap and easy and should get you by for years. Link to comment Share on other sites More sharing options...
Eagle Posted March 7, 2019 Share Posted March 7, 2019 3 hours ago, Jeep Driver said: And I have no idea why he is chasing a carb scenario............... And for that matter, if he was to go carbed he'd be better off using a MPI intake........2 bbl adapter would work out great, he'd have to make one of course. He did not mention but what? OBD1 ignition? .......TPS adapter to carb?...........IDK? Aftermarket ignition? '84 points distributor? what? I've considered converting my '88 2.5L to a carburetor. That single injector is pricey, and it's a bit of a kludge of a system. I'm old enough that I had almost 30 years of wrenching under my belt before I encountered my first fuel injected engine, so carburetors are easy peasey for me to tinker with. Much MUCH less work than converting a Renix TBI 2.5L to the Chrysler multi-port system (which is a far superior system). I think the ignition could remain untouched, but it would also be easy to swap in a distributor from an '84 or '85 Cherokee. But I don't think those used points. I think they were transistorized. Link to comment Share on other sites More sharing options...
carnuck Posted March 7, 2019 Share Posted March 7, 2019 I've considered converting my '88 2.5L to a carburetor. That single injector is pricey, and it's a bit of a kludge of a system. I'm old enough that I had almost 30 years of wrenching under my belt before I encountered my first fuel injected engine, so carburetors are easy peasey for me to tinker with. Much MUCH less work than converting a Renix TBI 2.5L to the Chrysler multi-port system (which is a far superior system). I think the ignition could remain untouched, but it would also be easy to swap in a distributor from an '84 or '85 Cherokee. But I don't think those used points. I think they were transistorized. 84/85 did indeed use the Motorcraft electronic ignition. The HEI or points distributor from a 2.5 GM 4 cyl (as used in boats and 60s Chevy II Nova) should work with the same gear swap as Chev inline 6 dist to Jeep in-line six. There is a 4.0L 4 bbl carb manifold available out there too. The single injector in the throttle body system isn’t too bad unless the Orings are leaking. I considered putting one on a 4.0L with the Renix flexplate to run the 4 cyl Computer for injection. The idea was bandied about years back on the Jeep Stroker Six and Renixpower yahoogroups. The AX4 or AX5 won’t bolt to a 4.0L, but Toyota used a variant of those transmissions. I considered getting a 2wd 2LT or bigger Toyota 4 cyl diesel for the swap. Sent from my iPhone using Tapatalk Link to comment Share on other sites More sharing options...
GrayWolf1691 Posted March 16, 2019 Author Share Posted March 16, 2019 Sorry for the late response I've been caught up with work. When I said knock sensor I meant the crank sensor. If motor mounts are no issue, would an obd-1 engine work to drop in and just swap my intake onto it? Or is that over-simplified thinking? Link to comment Share on other sites More sharing options...
gogmorgo Posted March 17, 2019 Share Posted March 17, 2019 From my research into swapping out my '91's 2.5L a few months ago, it seemed pretty clear that 2.5's are all essentially interchangeable. You'd just reuse your intake and exhaust on whatever new engine if you had to. The other option no one's suggested is disassembling the engine, and if possible, just slapping new rings into it. Give the cylinders a ridge ream and dingleball hone, and call it good. Of course it is a big job, and if I had to pay a shop to do it, I would prefer to pay for a full rebuild done properly. Not the cheapest route in that case. Link to comment Share on other sites More sharing options...
GrayWolf1691 Posted March 17, 2019 Author Share Posted March 17, 2019 I recall not being able to find a rebuild kit for the engine. Checked with autozone today since I was there and they don't have one. I'm figuring a newer engine would have more replacement parts available when needed hence the obd-1 engine and put on my current intake thought. Hone, rings and bearings were suggested already though. I can do a rebuild myself, just don't have the ability to swap it out at home. Link to comment Share on other sites More sharing options...
MuddFoot Posted March 17, 2019 Share Posted March 17, 2019 https://titanengines.com/engines/amc-jeep-150-87-96-complete-remanufactured-engine/Call these guys it's who I'm getting my stroker from. Sent from my moto e5 play using Tapatalk Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 17, 2019 Share Posted March 17, 2019 9 hours ago, GrayWolf1691 said: I recall not being able to find a rebuild kit for the engine. Checked with autozone today since I was there and they don't have one. I'm figuring a newer engine would have more replacement parts available when needed hence the obd-1 engine and put on my current intake thought. Hone, rings and bearings were suggested already though. I can do a rebuild myself, just don't have the ability to swap it out at home. Aside from the 84-85 2.5 engines which some had a smaller head bolt size and does not apply to you........here are the differences for you to be aware of- Later engines had a shorter crank snout, accessories were closer to the block, Renix engines were further from the block. Some claim that later heads were not drilled and tapped for the temp sensor.........yet I've not seen anyone claiming to have found one, mine was plugged. Other than that, all 2.5 engines are exactly the same............right on up through 2006 when production ended. Cam bearing are standard size, will be replaced by machinist with new, you will replace your cam, new cam and bearings. Pistons, machinist will tell to you what size pistons......bored 30 over........you will order 30 over pistons and rings. You will size rings yourself. Main bearings, I pay the machinist to measure main bearing clearances, grind or polish crank or new crank...either way he will measure. If main bearings are .010 under you will order .010 under. Same with rod bearings. Every part you need is readily available..........pistons, cam, bearings, timing set, gaskets...........just about anywhere. Have him check or shave the deck also..........head also......... Buy parts, not kits. Link to comment Share on other sites More sharing options...
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