'87 YJ 4.2 to 5.7 700r4 Advice - JeepForum.com
 
LinkBack Thread Tools
post #1 of 5 Old 03-25-2019, 05:07 PM Thread Starter
Stryker777
Member
 
Stryker777's Avatar
1995 YJ Wrangler 
 
Join Date: Feb 2010
Location: Missouri
Posts: 352
'87 YJ 4.2 to 5.7 700r4 Advice

I have a 92 GMC Z71 I'm about to pull from and drop in my 87 YJ. I can keep my Jeep transfer case and buy an adapter, or I think I can use the Chevy NP241c that is in the Z71. Both transfer cases hook up with the shafts to the left (drivers side). This will be my first swap. The truck runs well. I've had it for a few years and don't need it. My Jeep doesn't run well. The 4.2 was rebuilt but now had some severe engine problems and still has the BA10 transmission. Transmission is good but I want to replace it anyway. Tips or advice about which way to go? Pictures attached.

Attached Thumbnails
IMG_20190325_164200437_1553554703572.jpg   IMG_20160722_130426331_1553555234602.jpg  

92 XJ, 4.0 NP231 - Stock to rebuild for my daughter, 235x75R15s
95 YJ, 2.5 NP231- 1" shackle, 4.0 tb, 19lbs injectors, e-fan, 31x10.5R15 Treadwright tires.
93 ZJ, 4.0 w/AW4 NP231 - 2" BB, 1 inch spring lift, 31x10.5R15 Cooper AT3 tires.

In GOD we trust. It's a Jesus thing.
Stryker777 is offline  
Sponsored Links
Advertisement
 
post #2 of 5 Old 03-26-2019, 07:27 AM Thread Starter
Stryker777
Member
 
Stryker777's Avatar
1995 YJ Wrangler 
 
Join Date: Feb 2010
Location: Missouri
Posts: 352
After some research, I see I don't want to reuse the NP207 from the YJ anyway so I will be using the NP241c. Now to pick the SYE and what driveshafts to use. I'm going to swap the speedometer to an aftermarket electronic one so I don't have to do anything to the transfer case. I'm probably naive, but it doesn't look like this will be that difficult of a swap since I am pulling the whole thing, engine to transfer case, out of a running vehicle. Wiring will come out intact also. I'll be using a frame mounted fuel pump and the factory sending unit.

92 XJ, 4.0 NP231 - Stock to rebuild for my daughter, 235x75R15s
95 YJ, 2.5 NP231- 1" shackle, 4.0 tb, 19lbs injectors, e-fan, 31x10.5R15 Treadwright tires.
93 ZJ, 4.0 w/AW4 NP231 - 2" BB, 1 inch spring lift, 31x10.5R15 Cooper AT3 tires.

In GOD we trust. It's a Jesus thing.
Stryker777 is offline  
post #3 of 5 Old 03-26-2019, 10:07 AM Thread Starter
Stryker777
Member
 
Stryker777's Avatar
1995 YJ Wrangler 
 
Join Date: Feb 2010
Location: Missouri
Posts: 352
Looking at the JB NP241C HD SUPER SHORT SYE w/1310 CV Yoke for the SYE. Wondering what will have to happen for the front shaft.

92 XJ, 4.0 NP231 - Stock to rebuild for my daughter, 235x75R15s
95 YJ, 2.5 NP231- 1" shackle, 4.0 tb, 19lbs injectors, e-fan, 31x10.5R15 Treadwright tires.
93 ZJ, 4.0 w/AW4 NP231 - 2" BB, 1 inch spring lift, 31x10.5R15 Cooper AT3 tires.

In GOD we trust. It's a Jesus thing.
Stryker777 is offline  
 
post #4 of 5 Old 03-27-2019, 11:52 AM
Waternut
Senior Member
 
Waternut's Avatar
1988 YJ Wrangler 
 
Join Date: Sep 2016
Location: Macon
Posts: 885
You'll get more response going to a specific model forum but I dipped in here so I'll answer some of your questions.

I agree that what you're proposing is not terribly difficult but unfortunately, most answers aren't really black and white and it's not a quick weekend job. If everything went smoothly and you did weeks of prep work and nothing has to be redone, you might be able to knock it out in a weekend but consider that extremely unlikely case. So if you don't have a 3rd vehicle to get you to and from work for a week or two, this may not be the best choice. You can look at the link in my sig for my LS swap and get some ideas.

If you use custom engine mounts like Novak or something, you'll have to resize both driveshafts and you'll probably have to hammer the tub to give yourself clearance. You'll obviously need a new rear driveshaft anyway since you're going to an SYE. Those engine mounts are expensive and just look like a PITA. I bought some generic engine mounts and marked where my transfer case currently is. Then I basically welded in the mounts so my transfer case was in the same place. For your situation, maybe just mark the yoke for the front driveshaft. The last option would be to search used driveshaft lengths and buy one that will fit after you get it all installed...or just have Adams or Tom Woods send you one with the new rear driveshaft once you've measured for that.

The wiring might be a little tricky and you'll have to spend some time pouring over wiring diagrams for both vehicles. Do those vehicles have anti-theft system? If so, you'll need to get that removed from the ECU. You'll have to make a custom exhaust. You'll need to figure out a way to either adapt that transfer case to your skid plate or fab up a crossmember or skid plate to work. You'll need a floor/trans mounted shifter for your 700R4 and your transfer case since the transfer case shifters in jeeps are usually mounted to the transmission. You may or may not be able to reuse your throttle cable depending on length.

I'm sure I'm forgetting plenty of things but those are some things to consider before you jump in head first.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.



To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Waternut is offline  
post #5 of 5 Old 03-27-2019, 04:19 PM Thread Starter
Stryker777
Member
 
Stryker777's Avatar
1995 YJ Wrangler 
 
Join Date: Feb 2010
Location: Missouri
Posts: 352
Thank you for the information. Thankfully, I am not using either vehicle. I'm not starting the conversion till July or early August. I didn't think about the throttle cable. I'll measure travel on the truck and make one to match on my Jeep. Currently making a list of things needed for the conversion. I was thinking about the advance adapters saddle mount for the 350. Reviews say it puts a gen I in place with enough clearance for the distributer and bell housing. It's more expensive but has a nice design. Since I was replacing the engine and transmission anyway, this project has a decent budget. I was going to buy a crate 4.2, ax15, and put in an np231 I have sitting around. When I thought about using the Z71 drivetrain it seemed like a better move in the long run. Eventually I would want to ditch the 4.2 anyway. Current fuel pump idea is the E-8095. Novak headers will be installed. Then I'll have a shop make the exhaust.
I'll do custom shafts front and rear. Since it's longer and I'll be reducing the rear length, I'll welcome the extra length in the front. No alarms or anything on either. I'll probably build a crossmember for mounting. You bring up some good points and things I need to figure out still. Thanks again!

92 XJ, 4.0 NP231 - Stock to rebuild for my daughter, 235x75R15s
95 YJ, 2.5 NP231- 1" shackle, 4.0 tb, 19lbs injectors, e-fan, 31x10.5R15 Treadwright tires.
93 ZJ, 4.0 w/AW4 NP231 - 2" BB, 1 inch spring lift, 31x10.5R15 Cooper AT3 tires.

In GOD we trust. It's a Jesus thing.
Stryker777 is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JeepForum.com forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.



Email Address:
OR

Log-in











Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
headers for 5.7 hemi SKALA308 WK Grand Cherokee & XK Commander Forum 16 07-02-2019 08:54 AM
06 Grand Cherokee 5.7 Hemi to 2017 5.7 Hemi Swap KLK812 WK Grand Cherokee & XK Commander Forum 18 05-03-2019 10:01 AM
Advice needed : engine rebuild ? 4.2 BeepBeep_420 YJ Wrangler Technical Forum 10 04-15-2018 12:09 PM
1988 yj 4.2 need advice clint67 YJ Wrangler Technical Forum 2 11-28-2017 12:16 PM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome