1994 4.0 zj auto into a 1990 4.2yj 5sp

Area for post regarding Jeeps other than an FSJ. This area may contain technical post regarding those vehicles as well.
Posts: 1
Joined: Mon Nov 27, 2017 2:16 pm

1994 4.0 zj auto into a 1990 4.2yj 5sp

Postby Dan » Mon Nov 27, 2017 2:21 pm

I blew my 4.2 up and was given a 1994 zj complete. What will i need to swap drivetrain from zj to yj

User avatar
Site Admin
Posts: 9102
Joined: Thu May 12, 2011 5:53 pm
Location: Sonora, CA

Re: 1994 4.0 zj auto into a 1990 4.2yj 5sp

Postby Stuka » Mon Nov 27, 2017 3:56 pm

The Zj is going to be an automatic, are you going to use that transmission, or do you want to use the YJ's trans? The answer to this will determine if you need to mod the ECU for not using the stock trans which it controls.
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

User avatar
Posts: 461
Joined: Wed Mar 27, 2013 11:14 am
Location: Socorro, NM

Re: 1994 4.0 zj auto into a 1990 4.2yj 5sp

Postby Shagoneer » Tue Nov 28, 2017 8:19 am

Depending on how your crank looks in the 4.2, put that and the 4.2 rods into the 4.0 block and get a little extra torque while you have it apart.
In the market for a new FSJ

User avatar
Posts: 3507
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: 1994 4.0 zj auto into a 1990 4.2yj 5sp

Postby tgreese » Fri Dec 29, 2017 9:34 am

Kind of an odd forum to ask this question <scratchs head>

Maybe the poster thinks this forum covers ZJs?

A Wrangler forum might be able to tell you more about swapping the MPI 4.0 into a YJ. IIRC the ZJ and WJ 4.0L blocks are different, and won't land on the 258 mounts like the XJ 4.0L will. A ZJ forum would know more about that, or maybe the JeepStrokers forum. The have a blocks faq https://www.jeepstrokers.com/forum/view ... ?f=34&t=52 and seem to know quite a lot about swapology.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 FCA Jeep Cherokee KL Trailhawk, ECO Green

Return to “General Other Jeep Related Chat”

Who is online

Users browsing this forum: No registered users and 2 guests