Topic: four angry squirrels swap to a 4.0L in a 91 YJ

[swatsniper1s1k]

I know you all think i should just stick with the 4, but I'm gonna be driving across the country to move, and the 4 banger just won't do the trip. especially since i'm crossing 2 mountain chains and can barely get above 60mph. the rev is too high, the timing is a bit off, and the mixture is wrong and to fix it, i might as well drop the money on the 6 cyl.

However, I'm relatively new to messing around under the hood and i've never done an engine swap. i know i need to get the ax 15 to go with the 4.0 and trash my ax 5. and i know i need to change the main shaft of the np 231 t-case from a 21 spline to 23.

otherwise i need a complete parts list of what i need for this to work cuz i'm 20 and never really worked on cars except for the standard brakes, oil and 1 transmission drop. If anyone can point me in the right direction, it would be much appreciated.

[oldjeep]

Buy a 91 and up cherokee and use all the stuff from that.  Not worth trying to buy every individual part you need seperately.

[swatsniper1s1k]

buying a cherokee for a donor sounds pretty good. then i can just throw the 4 cyl into that.

[Jesse-James]

I agree, don't do it without a complete donor.

[chrisfranklin]

If you are a serious 4Banger guy, you buy a 4.0 YJ or TJ and swap in a 2.5.  Even better, you buy a new JK and pull the 3.8 V6 in favor of the 2.5.  Regear as necessary. 
 
If you are a serious 4Banger YJ enthusiast, you do the above and -- on a TJ or JK -- add a YJ-type grill you fabricated.       

[st.chevrolet]

That swap is a lot more work than you think it is. ie; cutting motor mounts off of frame and replacing (read welding on) with 4.0 frame mounts. The smart thing to do in your case and with your experience, is sell your Jeep and buy one with a 4.0.

[Bounty Hunter]

^^^What he said, sell it and buy a 4.0L jeep, or swap in a worthwhile engine like a v8.  Make the money, time, and trouble worth it.  Swapping in a 4.0L will leave you with another run of the mill 4.0L jeep with a hacked up install (read: non-factory).

[Jeffy]

Although, if your Jeep is in 'great' condition and not a rust bucket then it might be worth it.  With that much work, you might want to consider a V6 or a V8 since it isn't much more.

[jagular7]

Backing up what St. Chevrolet, Bounty Hunter and Jeffy have suggested.

Do some local research as to go to a local 4wd shop and get an estimate (even over the phone) to what it would take to do a swap with you already having all the hardware and wiring. Basically what the labor and time it would take to pull, demol the 4cyl/trans/wiring and install the 6cyl/trans/wiring. Don't forget the fuel system as well.

If you are moving across the country from coast to coast, you will find that even if you have a 6cyl, you are not going to be pulling any real weight in a trailer with a short wheelbase Jeep. The recommendation difference between the 2 engines is only 500#s. To add, your new location may have EPA regs for the new engine. More research to be concerned with.

Either sell what you have, keep what you have, but recommend not to swap anything till you know the details of the removal and install as well as the legalities of the new location of your living state.

I pulled a camping trailer across CO rockies on I-70 last Sept from KC to Moab. It weight 1300#s when I got home so it was heavier when I started out (firewood). I pulled it up through the Eisenhower tunnel going 25 mph at ~5000rpm in first gear. For the 20 minutes it took to climb that, I still am running the 4cyl with the auto. It does fine for getting to/from the trails, driving the trails, and for putsing around on really nice days around town. Yah, more power would be nice, but the <3% of the driving requiring bigger engine, I can live with it.

[swatsniper1s1k]

the frame and body are completely clean, no rust whatsoever, and i've already invested a lot of work into tires, fender flares, the soft top, a new paint job, a new carpet, and $600+ in a sound system. i'd rather keep that since it is my first car, and just get a new powertrain. last time i suggested the v8 swap, y'all complained about how it would ruin my balance and weight distribution and all. i'm thinking if not a 4.0 then it'll be a fuel injected 305 out of a early 90's camaro. it seems as tho that's my best bet, and there is a bell housing adapter to an ax15. i'm keeping it manual trans. auto is out of the question. the turbo idea is a good power adder it seems, but it's just too much work, having to fab custom manifolds and the like, i just can't afford all of the time the install and the adjusting it will take. supercharging is ok, but the kits are for tj's and are more useful off road then on highways. i'll just work a 305 or 350 with an ax15 and a lift kit that will support that engine...

question is, does the rear diff absolutely need to be changed, or can it stand the 305 option? and if so, what do i upgrade to without breaking the bank or going too hardcore...

[swatsniper1s1k]

and as for the trailer pulling weight, all i need is a 4'x8' trailer with a couch, a bedframe, a dresser, the bed and some kitchen stuff thrown into it. it'll maybe top out around 600-700 pounds over the empty weight of the trailer.

[st.chevrolet]

Before doing anything drastic, you might want to get the timing and mixture problems corrected. Unless your motor is totally worn out it should do a lot better than barely 60mph. You also mentioned revving to high, what gear ratio are you running? And I really do not understand what the big problem of crossing two mountain ranges is. I live in the Province of British Columbia, Canada, which is pretty well all big mountains. When I leave my home in the Okanagan Valley to head to the west coast, I start out at 1500' above sea level and climb a winding 6.5% grade for 19 miles to 5760' above sea level. My stock 4 cyl. 5 spd. YJ climbed it with no problems, yes it spent a lot of time in 3rd gear and was definitely no ball of fire but it has done it many times. I have since turbo charged it and it pulls that grade as good as a 4.0 now.

[swatsniper1s1k]

Before doing anything drastic, you might want to get the timing and mixture problems corrected. Unless your motor is totally worn out it should do a lot better than barely 60mph. You also mentioned revving to high, what gear ratio are you running? And I really do not understand what the big problem of crossing two mountain ranges is. I live in the Province of British Columbia, Canada, which is pretty well all big mountains. When I leave my home in the Okanagan Valley to head to the west coast, I start out at 1500' above sea level and climb a winding 6.5% grade for 19 miles to 5760' above sea level. My stock 4 cyl. 5 spd. YJ climbed it with no problems, yes it spent a lot of time in 3rd gear and was definitely no ball of fire but it has done it many times. I have since turbo charged it and it pulls that grade as good as a 4.0 now.

i'm running whatever the stock gear ratio is. the main bearing in the transmission is crapped out too. the motor has 160k miles on it, and it's only a matter of time before it's dead. running 31" tires on it might be part of the issue, but all in all i still need to tow my stuff out there, and my engine will most likely die on the trip or break down and i'll have to drop a grand into getting that fixed at some shop. My current thoughts are throw in a chevy 5.0L or a mopar 5.7L hemi. the biggest problem with the engine is trying to maintain highway flow, which is 5-10 mph over speed limit which is 65-70 mph for most of the drive. towing the trailer, with total weight in the 2000 pound range, will make getting to those speeds even harder.  plus instead of snail-ing up to speed i'd like to be able to accelerate pretty well.

[Bounty Hunter]

The 5.7L is a much better engine than the 5.0L, then there's the 5.3L which is better than both.

[jagular7]

For options on the engine, you may want to stick with the engine's mfr trans as well and mate that to the 231 you have in the YJ. Or late model GMs have the driver drop tcase so swap in the whole donor. You will need to figure out the tcase output if you want to do a SYE or not. Yes, your rear axle will probably need a change as well since you described a well-used YJ. Similar for the front axle. Swapping axles into a YJ is much simplier than TJs. From whatever donor they come from, you may have the option to do a SOA or the SUA. That will depend on your pocket book.

As for the engine, V8s are not bad to toss into a YJ. The stock YJ trans could possibly handle the hp/tq but since there are lots of miles, I'd look into rebuild or replacement. You should also look into the cooling of the new engine.

Check with your local Jeep club for support to these options. I really think the biggest hurdle will be the new location of accepting the engine swap and meeting the EPA regs. Once that is acceptable, then next hurdle is the pocket book and time clock.