Info from my YJ Chevy LS Swap -
LinkBack Thread Tools
post #1 of 2 Old 12-10-2010, 11:34 AM Thread Starter
Registered User
1989 YJ Wrangler 
Join Date: Feb 2010
Location: lansing, MI
Posts: 8
Info from my YJ Chevy LS Swap

If any one is interested, here is some information that may help with a LS type Chevy engine into a Jeep Wrangler. This is what I discovered
in the process of putting one into my 1989 Wrangler. It was originally a 258 with a Puegot trans. I swapped in a 4.O HO and that worked OK
The trans then crapped out and it was going to cost a fair amount to replace it with a AX15 and the 4.0 was still fairly lame, so the 5.3 project
was started. I only put about 400 miles on it since the swap but I am extremely pleased with the way it turned out- drives great and it get's
better gas mileage and what a power difference. It will be my daily driver next year when the snow melts. The cost of doing this swap so far
is less than $2000 but a new radiator will take me beyond that. It would cost much more if you do not do all your own work. The big cost will
be the engine. The amount of miles pretty much sets the price. Mine was $525 with all accessories (starter, alternator, PS, brackets, exhaust,
computer, wiring harness, computer,etc). It had 130K on it. Don't make the mistake of buying it without all this as it will cost a ton to
piece all this together. They had more of them at this price, so I guess it's normal. I have 240K on the one in my work truck, so the mileage
didn't bother me. I do not have pictures yet, but if anyones interested, I can take them in the spring.

Engine/trans Mounting and exhaust
When I originally started the project, I was on a tight budget. I wanted the transfer case in the stock position so I could use the same drive
shafts. I then worked forward from there. The stock off set of about 7/8 of an inch to the passenget side was kept to give steering collumn to
power steering clearance. In the end, this was actually the best position. It gave just enough clearance to the rear of the
engine to firewall and there was enough room for the electric fan in front. First to be positioned was the trans mount. A 1991 S10 mount was
used by just drilling holes in the stock cross member/pan. I had to drill holes and then access holes for the nuts as it ended up in a reinforcing
section. This put the transmission at about the right height without any further mods required. The 5.3 was mounted using the mounts from Novak.
I got a real deal on the kit on Ebay. I also bought Hooker shorty headers on Ebay. Hooker was selling them as "scratch and dent" but there was
nothing wrong with them. When I tried using the mounts with the headers, the passenger header interfered with the Novak mount. This was fixed by
moving the square hole in the plate that mounts to the engine 1.25 inches forward. All this required was drilling a hole and then shaping the hole
into a square with a file for the mount carraige bolt. The passenger header dump was close to the starter but has not been an issue yet. The 2004
starter is much smaller and is what I will get if there is a future heat issue. The exaust was fabbed out of 409 stainless. All the parts were from
Ebay and Summit. The Y-pipe was made out of 2.5 inch which then went to 3 inch after the Y. I used a prefabbed Y that was much easier than making
one. The stainless was very easy to work with and can be welded with either stainless or mild steel MIG wire. It was easier to work with than
aluminized steel and will last much longer but did cost much more. I bought U bends and straight pipe. Looking back, I did not estimate the exhaust
system price initially high enough, I ended up spending around $400 on the exhaust but hopefully will never have to replace it.

Transfer Case
I used a Np231 out of a 1991 Chevy S-10 Blazer. A NP233 from a ChevyY could have also been used easily but the elctric T case does not have
a nuetral, which I wanted. The 231 T-case had 6 pinions in the low range planetary. It had the same input spline as the 4L60E transmission.
The chain in it was also wider than the the one in the Jeep version of this transfer case. I installed a JB slip yoke eliminator kit which
fit the Chevy unit without issue. The Shift arm (outside) from the Jeep T-case was used. This allowed using the original Wrangler shifter
(with modified mounting points). Having a cable speedometer, I used the Jeep speedo drive. I now had the problem that I did not have a
transmission output shaft speed sensor. I saw many kits but they were pretty expensive. I went a different route. I used the ABS sensor on
the 8.8 axle! This worked great and did not cost anything. I just wired it in. The PCM programming needs to be changed in 2 places. These
are for the pulses per mile for speed and the output shaft pulses per rotation.

to get these:

pulses per mile= 5280*12*108/tire diameter*Pi (The 108 comes from the pulses in the 8.8 rear end per axle revolution)

pulses per revolution= 108/rear end gear ratio (in my case 108/3.73= 28.95 pulses per revolution, normally 40 in a GM truck)

The transfer case adapter came from Ebay. There are many people selling them from $15 to $30. They are commonly referred to by the term 5 bolt
as they have 5 bolts to mount the transfer case. There are 3 different verions made by GM.
The part number for each of these is cast right into it so they are easy to identify.

15028096 this is for a standard S10 Blazer or S10 pick up in the late 90's. This is the one I used. This is the easiest one to find.

15028097 this is the one that came with ZR2 S10s. This adapter lowers front drive shaft the most. It has the best chance of interfering with
the stock crossmember/transmission pan unless the transmission mount is raised to give added clearance. It would be best for lots of lift.

15996882 this one came in all wheel drive Astro vans 1998-05 and maybe others. This is the one I should have used. It has the least amount of
transfer case drop. I do not think I would have had to modify my cross memebr with this one. I just got in a hurry.

The last thing I did was remove the front bearing retainer and weld it up and machine it back down so the bearing reatainer had a slip fit into
the transfer case adapter. A sleeve could have also been made to reduce down instead of welding. I'm not sure if this is really needed as I hear
constantly about guys using just a clocking ring to adapt- without a locating slip fit.

The original wiring harness was used that came with the engine. The PCM was placed where the original Jeep one previously was. If the old
PCM mounting brackets are removed, the Chevy one fits right in and was tight enough that it did not need any brackets. It basically pushed
between the heater ducts and was held in from moving rearward by the glove box. The wire harness was then rerouted through the Jeep firewall
gromet that had the previous engine wires. This was a chore as each PCM wire had to be done one at a time by removing it from the connector
and routing it through the grommet and putting it back in the connector. This took a couple hous but I did not have to put the PCM underhood.
It also gave a clean appearance as the all this wiring was hid and was protected. I did update the PCM to a 2004 unit so I could run the
returnless fuel system. All the wires were there, the only major change was around O2 sensor wiring as the PCM controls when the heaters come
on and did not for the 2001. I also needed to change the red PCM connector plastic to a green one. The fuse box used was from a late 90's
Astrovan ($5) at the local junk yard. It had more than enough relays and fuse spots.

Fuel System
The stock 16 gallon fuel tank was used which was a not a intank pump. A MSD inline pump was used. This fuel pump I would not recommend to any one.
The pump can be heard over the exhaust. The next modification will be a intank pump in the plastic 20 gallon tank I bought. A new skid plate/mounting
plate needs to be found as the one I have is rusty. A AC Delco returnless regulator/filter was used and mounted to the frame. The returnless fuel
system made it easier to plumb and the engine was converted by just changing the fuel fuel rail with one from Ebay ($15). I would highly recommend
anyone doing this swap or any other EFI swap start with a in-tank fuel pump as they last longer and are quieter.

Radiator and Plumbing
The heater hoses required nothing special. I have seen people buy the hoses with a formed 90 in the end for the engine. I used straight bulk
hose with out any issues. The stock radiator from the 258 was used. I will replace this with an after market on next year. It was large enough
to run around the streets without it getting to hot but will be a problem at slower speeds and larger loads. With a 160 degree stat, the thing ran
around 198 degrees telleing me it's time to get a bigger radiator. The stock Jeep outlets seem to be best. The aftermarket small block Chevy unit
are harder to plumb hoses to as the hose fittings are larger. A straight CSR themostat housing was used ($39). This housing uses the standard small
block Chevy thermostat. I thought this may be a problem as it is different than the stock thermostat in the way it routes water through the heater
core. This part worked just fine and the heater seemed to work fine also. The lower radiator hose was a flxible unit that was 30 inches long with
1.5 inch ends ($18). The upper hose was cut out of the original upper radiator hose from the truck the 5.3 came from. The trans oil cooler in the
radiator was used and the oil never got to hot. A electric fan was mounted to a shroud and put on the radiator and was controlled by the PCM. It
was set to come on at 185 degrees F and off at 180 degrees F.

Power Steering
The power steering hoses from a 258 wrangler worked just fine. I had to unscrew the pressure sensor out of the 5.3 power steering pump and then
screw a fitting out of the 258 pump that the hose screws into. This was the easiest part on the swap.

Throttle Cable
I did not do drive by wire as I did not have the parts. I did not think it would be worth the added cost but would have definitely used it if I had
the parts. The throttle cable I used was from a 2000ish S10 with a 4.3. The fire wall side needed the plastic wings filed off the cable and then
fit perfectly. For the engine side, I cut the section from the S10 bracket and welded it into the 5.3 throttle bracket. This worked great and only
took about 1/2 hour to make. The 5.3 truck cable was to short and also had a round end going into the firewall ( Jeep is square).

Rear End/drive shaft
After reading all the posts, I decided the 8.8 out of a Exploder was the best option. This swap was super easy. I re-used the spring mounts from the
8.8. The axle tubes were welded in. Shock brackets were fabbed out a chunk of 2"x3" by 1/8" steel. A trac bar mount for the axle was fabbed. This rear
end also saved me many dollars because of the speed sensor described in the transfer case section. The gear ratio was 3.73 and it had a trac loc. This
rear end costed all of $160 on Craigslist. The drive shaft also came from the recomendations of this web sight. It was a Jeep Cherokee front shaft
from the local junk yard ($40) with another $70 bucks for shortening and one new U-joint.

A core 1999 4L60E was purchased. I open it up and had to replace alot of parts. A planetary gear set was junk. All the clutch plates and steels
were replaced. The 3/4 clutch was upgraded and Alto reds and kolene steels were used. A corvette servo was added. A Raybestos Pro series band was
used. A "Beast" sunshell was installed. Sonnax pinless acumilators were used as the stock stuff was wore out. After seeing all the damage inside,
I don't think I would uses a 4L60E without pulling it apart first even if it seemed to work OK when pulled. All these parts worked fine together without
any more work needed although the shift times were shortened in the PCM for performance. The trans mount from the 1991 S10 was used.

Steering Column
The steering colunm from the 1991 S10 was used. This was done to have a column shifter and to get a tilt wheel as my Jeep was origionally a stick.
There was one bracket on the front of the column that needed to be removed by cutting the weld around it and slippeng it off. I used the 4 inch grinder.
The column then slid right in and all electrical connectors plugged right in. The shift linkage was made by taking the original S10 unit and heating and
bending until it fit. The linkage did not go to the frame like it did in the S10,it went directly to the transmission. The transmission arm was made by
welding the old frame arm and a transmission arm together after cutting to shape. Using this column allowed me to have a park lock also, so I don't forget
to put it in park as the key wouldn't come out. It did not look like the Lokar kits were going to work and they are expensive.

The original 6 cylinder tach was removed and I Ebayed up a 4 cylinder. A 4 cylinder tach will supposedly work with the output of the GM PCM. It did not
work though. After reading some other web sights, evidently a resistor can be added to 12 volt power and then the tach will function. I have not verified
it yet.

Hope this helps someone!

rb440mike is offline  
Sponsored Links
post #2 of 2 Old 03-10-2011, 06:05 AM
Registered User
2004 TJ Wrangler 
Join Date: Nov 2010
Location: Bountiful, UT
Posts: 141
Hello from in town!

Great info, I am hoping to do this myself one day.

I can only give you what I think you said you thought you wanted.
Dentedvw is offline  

Quick Reply

Register Now

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

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


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

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

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
Need some info and advice on ODBII Chevy V8s for a swap YeepieJeepie Engines & Drivetrain 14 01-29-2014 02:25 AM
chevy 350 swap into zj jklisiewicz Engines & Drivetrain 0 09-12-2009 08:16 PM
Who has done a 4.3 Chevy swap? danholovic Engines & Drivetrain 2 10-29-2008 08:41 PM
chevy 4.3 swap lurkeryj Engines & Drivetrain 2 04-28-2008 10:08 PM
Chevy swap on XJ 89'XJ Engines & Drivetrain 4 09-28-2006 12:51 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