Replace 4cyl engine in my YJ Wrangler

spartan74

New member
We've got a 1990 YJ Wrangler(2J4FY19P4MJ____) that came to us with a broken 5 speed tranny and a questionable rebuilt 4 cyl. My son drove a 4 cyl Wrangler on a used car lot and found it to be a major Wimp from a performance standpoint. Rather than throwing $ and labor into getting the 4cylmotor running we're contemplating moving to a larger engine. We've heard that doing this is no small feat. We'd love to hear from others that have undertook this task and the resulting lessons learned along with suggestions on an good engine to use. We'd especially wonder how the matchup between the original tranny and other replacement engine was made.
Spartan74
 

Late reply here, been away. I have not done the swap but there arr many threads on it in yhe build section.
How big are you going and what do you want to do with the vehicle after?

Some go to 6 cylinders and some go 8. There is a good website bor transmission selections or adapters for the swap.

Novak Conversions Home

Never look down on anyone unless you are helping them up - Jesse Jackson
 
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We've got a 1990 YJ Wrangler(2J4FY19P4MJ____) that came to us with a broken 5 speed tranny and a questionable rebuilt 4 cyl. My son drove a 4 cyl Wrangler on a used car lot and found it to be a major Wimp from a performance standpoint. Rather than throwing $ and labor into getting the 4cylmotor running we're contemplating moving to a larger engine. We've heard that doing this is no small feat. We'd love to hear from others that have undertook this task and the resulting lessons learned along with suggestions on an good engine to use. We'd especially wonder how the matchup between the original tranny and other replacement engine was made.
Spartan74

I had a 91 YJ with a tired 6cyl. Got a 350 that was redone for off road. 340 hp, 380 ft lb of torque. I found out after I could have gone to Chevy and got the motor for a quarter of what it cost me from the specialty shop. It is really not that much to swap it out. You get a bell housing from Advance adaptors along with what ever fly wheel you want but if you finde a good 4 whl shop they can do everything. New engine $2500-$3500, trany if you can find one $1500 and the Advance Adaptors parts another $1200-$1400. I had no power problems but make sure you get the largest radiator you can.
 

I used a 302/c6 and whatever t-case came in an 85 or 83 bronco. I had to cut the motor mounts and weld in replacements. I had to get a rear driveshaft made but it went in fairly easily for someone who knew nothing about putting a v8 in a yj.

The stock 4.2 radiator hooked right up to the 302 and the stock gauges worked fine because I used the 4.2 senders in the 302. The exhaust lined right up with the stock Ford exhaust were I cut it behind the manifold but in front of the cat. Same diameter and ran in the same spot so I just welded it together. I was already running a holley electric fuel pump and return line to keep pressure where it needed to be because I was already running a small holley four barrel on the I6.

If I had actual experience and stayed on it, it could have been done in a weekend and with buttoning up another weekend or two but I have a hard time staying on track so it took me months.

I hear the Chevy engines are easy too, though.
 
I swapped out a '95 2.5 AX-5 to a '94 4.0 AX-15.....You'd think easy peasy lemon squeezy right? WRONG!!!! Pain in the ass nothing interchanged and cutting out and repositioning the right motor mount....
I got too deep into it to turn back and just small block it. But, I scored on the 4.0 being sewing machine tight...Wound up getting a rebuilt tranny and the SYE'ing the transfer case to get it all in line and smooth
running. Still a little under powered mid-range RPM's with the 3.07 gears...But they make a bolt on Super Charger that I'm eye balling...
 

hello guys,


Replacing the 4-cylinder engine in your YJ Wrangler is a significant project that requires careful planning and execution. Here are some general steps you can follow Decide on the replacement engine: There are several options available for a YJ Wrangler engine replacement. Some popular choices include the 6-cylinder engine from a later model Jeep, a V8 engine, or a rebuilt or upgraded version of the original 4-cylinder engine.Gather necessary tools and equipment: You will need a variety of tools and equipment to remove the old engine and install the replacement. This includes an engine hoist, engine stand, torque wrench, socket set, wrenches, and various other tools.
 
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