Jeep Wrangler Forum banner
  • Hey everyone! Enter your ride HERE to be a part of September's Ride of the Month Challenge!
1 - 20 of 48 Posts

·
Registered
Joined
·
42 Posts
Discussion Starter · #1 ·
I'm doing this swap because I've done plenty of other swaps (5.2 in a TJ, 4.7 in a JKU, 360 in a DJ5, etc) and wanted something a little different. I've never been interested in GM swaps, because the Mopar V8s are simply a better engine for a Jeep. Plus, everyone does them. That problem has been solved many times. Its not the most powerful engine, but it makes good power (225 lb⋅ft (305 N⋅m) at 2800 rpm) for its weight and size. Its small and should fit easily.

Originally, I wanted to do a GM 4.2L I6 swap. That engine would be great. I found Cornchips thread and started bugging him with questions. If you want an automatic or are a machinist that can make a custom flywheel, go with the 4200. Cornchip is very helpful and a lot of his advice (along with other posters in the thread) will be reflected here.

https://www.wranglerforum.com/f218/amc-4-2-to-gm-4-2-swap-thread-information-2167890.html

GM had a family of Atlas engines including the 4200, 3700, 3500, 2900, and 2800. I considered the GM Atlas I5 3700 which is an updated version of the 3500, but its a unicorn that's very expensive.

Major Parts include:
1. 3500 Engine (2006 Chevy Colorado)
2. AR5 (2004 Chevy Colorado)
3. NP233C (2003 Chevy Blazer)

AR5
Its nearly identical to the AX15 and most of there parts interchange. The AR5 is 2 inches longer and the shifter is located ~5 inches back compared to the AX15.

NP233
Electronic shift NP231-like transfer case with a 5 bolt housing to match the AR5. I plan on getting the electronic components to work, so I can use Push Button transfer case control. I did something similar on a 99 TJ.

I purchased a Ram Charger NP241 transfer case (~1990) of Craigslist awhile back because they have the same shaft output everyone sells in there standard SYE kits. The Ram Charger 241 tailhousing won't work on an NP231, so all you need is a tail housing and you've got an SYE. A jeep SYE NP231 tail housing can be purchased stand alone from Rugid Ridge. Unfortunately, that doesn't support the Chevy VSS and tone ring.

JBConversion has a tail housing bearing adapter that will work, but it comes as part of there $380 kit(#16-1205-XXXX). I sent an email asking if they would sell it to me separately, but didn't get a postive response. I purchased a tail housing adapter from IronRock Offroad as part of there 32 spline HacknTap hit.

I will need to modify the output shaft in the same way JB conversions modified the shaft in there kit to make it work with the GM VSS. You can see the modifications in the installation instructions. They cut two new snap ring groves offset by ~1/4in from the original groves. This seems fairly easy to do with a grinder, but I'm a little nervous about doing it myself.

JB Conversions, Inc.

https://www.ironrockoffroad.com/prod...nator-kit.html


Other Considerations:

Accelerator Pedal: These engine use an electronic accelerator pedal. I have the pedal, but have checked fitment yet.

Fuel: Custom AN lines using the 2000 Corvette fuel pressure regulator.

Power Steering: The 3500 series PS pump has the same size fitting as the 2.5L jeep PS pump, but the 3500 PS pump is on the passenger side. I'm hoping the longer engine will allow the 2.5L to reach. If not, I'll try getting a hydraulic shop to mesh the 3500 and jeep lines together

Clutch: Use the Russell 640281 -3 AN SAE Adapter Fitting along with AN3 lines

Wiring: I'll splice the jeep and Chevy wire harnesses together.

PCM: The 3500s use P12 PCM, I'm working on "hacking" it based on the PCMHammer tool available for GM V8 engines. I can modify the VIN. I should be able to program it with stock manual transmission software.

Clutch and Transmission

This engine was mated to an automatic, so I had to remove a large bushing. I was unable to get it using the Advance Auto Parts loner tool. I purchased a tool from Amazon that worked after some modification.

https://www.amazon.com/gp/product/B013U0E5YS/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

I had to grind down one of the larger extractors, because the next smaller one was to small.

After that I was able to install the pilot bearing and clutch. I purchased a cheap angle gauge from amazon because the flywheel torque is 30 lbft + 45 Degrees.

I was stuck on the clutch bolts, because there is no obvious ARP kit. ARP 103-2201 is very close, so i ordered it. GM PN#11518102 is the OEM solution (,M8X1.25X15.15,10.15 THD,10.9).

That's as far as I've gotten...
 

·
Registered
Joined
·
170 Posts
What engine and transmission do you currently have in your YJ? Figure you'll be able to save the driveshafts as-is?
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #3 ·
I've got a 2.5 / AX5. I hope the from drive shaft will work as is, but I'll need a new rear shaft.
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #4 ·
transfer Case Mods

Here are some pics of the transfer case modification. I didn't take a photo of the Front Transfer Case output gear/shaft which must be replaced with the 231 equipment. The seal must be removed in order to swap the gears. One photo shows the NP241 Ram Charger Output shaft next to the NP231 output shaft. I had to put the 233 gears on it.
 

Attachments

·
Registered
Joined
·
170 Posts
Any considerations on cooling? These engines have coolant locations at midway and favour the common Chevrolet coolant placement on the radiator. Like a fool, when I parted my 89 YJ and removed my 305 TBI....I just took everything to the scrap yard. Part of the pile of junk was my Chevy conversion radiator.....mind you it was 20 years old with a bunch of winters on it. This particular rad was from a bit of an urban myth at the time (read about in a 4x4 magazine). Made by Modine, this brass and copper rad had a massive 4 core with factory pressed tanks as you would see in a factory made product. The myth goes that a decent number of Jeep YJ's were converted in the US to be used in Japan and had Chevrolet drive-trains. Part of a proper conversion is reliable components like a purpose built radiator. Since this was pre-internet...I can't find reference to it today. So it's just a myth...and not worth talking about here in Radar's build thread.



I kick myself for chucking it, but getting a re-core these days isn't what it used to be. It's a lost skill and costs far beyond that of some newly created conversion rads. I pulled the hammer on a rad made by Superior Radiator in Mt.Clemens Michigan ($225 US). Just need to get my shroud made to adapt my Taurus efan.



 

·
Registered
Joined
·
42 Posts
Discussion Starter · #8 ·
It would be interesting to know if that's real. I didn't getting any obvious hits from google.

I have considered cooling, but planned on making long hoses for the stock radiator. I might reassess that decision once its in. I put a radiator like that in a TJ with a 5.2. They are very nice.

I already did an e-fan for the 2.5L with the understanding that it should make my swap easier. I made a custom fan shroud and used the volvo e-fan. I removed it from the fan shroud, bolted it my custom shroud, and mounted used the volvo relays to the shroud. Volvo uses a plastic piece to mount the relays. I took the piece, drill two holes in it, and it mounted easily to the new shroud. I'll try to take some pictures later today.

This thread has good information about using the volvo fan and has pics of the relays with wiring. I actual purchased a Taurus fan, the volvo fan, and another one that people recommended on the forums, but went with the Volvo fan.

https://therangerstation.com/tech_library/volvo_electric_fan.shtml

I plan on heading to the Junk Yard this morning to look for T-case studs. Then, I'll head to a local machine shop and ask about cutting new snap ring groves in the 241 output shaft. If I find a ram charger in the JY, I might pull the shaft. Most Self service junk yards get a little confused when you put an internal t-case part on the table, so they only charge 20-30 for the part. I might try doing it myself, if I have a backup.
 

·
Registered
Joined
·
170 Posts
Stock Jeep radiator is more than fine with these Atlas engines. FYI, the 4200 in a Trailblazer flows from the passenger side to the top tank and downwards to the bottom and back to the inlet with the thermostat behind the alternator.



Sounds like you have that all under control with what you have on hand. Volvo fans are great. I like the way the fan shroud comes apart vs the way I had to cut mine apart.
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #10 ·
Some useful wiring information for the Jeep YJ primary engine to chassis wiring connectors C105 and C107. These pinouts are not defined in my FSM, so I had to generate them.

C107 YJ

1 C20 BR/RD A/C Select
2 C91 LB A/C Request
3 A14 RD/WT Fused 30Amp B+ Power to the PCM
4 C13 DB/OR Ground for coil side of the A/C Compressor Clutch Relay
5 T41 BR/YL Park/Neutral Position Switch to PCM (grounded to starter relay when starting)
6 G20 VT/YL Engine Coolant Temperature sensor to C112 (Gauges)
7 G50 WT/YL Start/Run B+ to Datalink Connector and PCM
8 G3 BK/PK PCM to MIL Light Gauge via C114
9 V40 WT/PK Brake Switch to PCM
10 K51 DB/YL ASD Relay Ground From PCM
11 K54 OR/BK Upshift lamp driver from PCM to gauges
12 G21 GY/LB PCM Tach Signal to Gauges
13 D20 LG SCI Receive
14 D21 PK SCI Transmit
15 G7 WT/OR Vehicle Speed Sensor
16 K7 OR 8V to Cam and speed sensors , NOT NEEDED


C105
105 1 T40 BR Start Relay output to starter Motor Solenoid
105 2 C3 DB/BK ?
105 3 A141 DG/BK 12v to Fuel Pump from fuel pump relay
105 4 G4 DB Fuel Tank level gauge Goes through C112 to the gauges
105 5 L1 VT Power to backup Lamps S304 (8w-70-15)
105 6 C20 BR/RD From A/C Lower Pressure Switch to Relay
105 7 G7 WT/OR From Vehicle Speed Sensor
105 8 A142 DG/OR ASD Relay Output to Injectors
105 9 G5 DB/WT Ignition switch Start-Run B+ to Backup lamp via reverse switch
105 10 T41 BR/YL From Starter Relay Control to ground
105 11 K7 OR 8V Sensor Supply from PCM 8W-30-10
105 12 B3 LG/DB LR Wheel Speed Sensor
105 13 T22 DB/TN TCC Solensoid from relay output
105 14 G60 GY/YL Oil Pressure Sending unit to gauge Goes through C112 to the gauges
105 15 B2 YL RR Wheel Speed Sensor ABS Only
105 16 B1 YL/DB RR Wheel Speed Sensor ABS Only
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #11 ·
Master Cylinder pluming. I put it together, then realized it wouldn't install without breaking it apart, because the line won't bend enough to fit within the bellhousing. The YJ master cylinder requires an AN4 fitting (652504ERL Clutch Adapter Fitting -4 AN) and 501902ERL (3AN to 4AN adapter) to convert between them.
 

Attachments

·
Registered
Joined
·
42 Posts
Discussion Starter · #12 ·
Motor Mounts

I've been working on the motor mounts. I plan to make the engine side mounts in two parts that can be welded together during install. I designed some simple brackets to hold the two sections of the bracket in place, so I could weld them together. I also designed some drill guides.


https://www.tinkercad.com/things/lpAl3dseVE7

https://www.tinkercad.com/things/eWNU3bffxQ1

https://www.tinkercad.com/things/dj9VubIM77t

The pictures show both brackets in the 3d printed fixtures. along with a finished product. My welds need some work, but I'll add more support once the engine is installed and both halves are welded together.
 

Attachments

·
Registered
Joined
·
170 Posts
Master Cylinder pluming. I put it together, then realized it wouldn't install without breaking it apart, because the line won't bend enough to fit within the bellhousing. The YJ master cylinder requires an AN4 fitting (652504ERL Clutch Adapter Fitting -4 AN) and 501902ERL (3AN to 4AN adapter) to convert between them.

Yes...the window in the bell housing won't allow anything longer than the original quick disconnect. Do you connect the extended line first or put it on after?.....I'm thinking after.
 

·
Registered
Joined
·
170 Posts
I've been working on the motor mounts. I plan to make the engine side mounts in two parts that can be welded together during install. I designed some simple brackets to hold the two sections of the bracket in place, so I could weld them together. I also designed some drill guides.


https://www.tinkercad.com/things/lpAl3dseVE7

https://www.tinkercad.com/things/eWNU3bffxQ1

https://www.tinkercad.com/things/dj9VubIM77t

The pictures show both brackets in the 3d printed fixtures. along with a finished product. My welds need some work, but I'll add more support once the engine is installed and both halves are welded together.

How's your lower rad hose looking for clearance with the steering shaft? The 4200 has a larger cased alternator that requires a different thermostat housing. It's angled back and up with a pressed in SS metal tube that turns in the direction of the steering shaft. It would most definitely rub unless you could raise the engine a solid inch or so. The 2800,2900,3500 and 3700 have a smaller alternator with a straight out 1 1/4" neck. When you get that far....snap a picture to show what you ended up with for clearance. I'm guessing plenty as your sitting back some with one less cylinder. I'll post a picture of my stock modded neck to create a better position avoiding the steering shaft HERE.
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #15 ·
I put the slave in, then connected the extended line. Its very tight in there.

I hadn't considered the possible interference with the steering shaft, but (now that you mention it) it makes sense that there might be some interference. I'll go take some measurements tomorrow. I need to think through the cooling modifications.

I'm not sure when I'm actually going to install this thing. I would like to drive it during the spring, because that's the best top down weather. I might not tear into it until late june. I would like to get as many things ready before hand as possible in order to minimize down time. This type of thing usually takes me 3-6 months, but that really sucks.
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #16 ·
I took a look at radiator hose clearance and it seems okay. It might be awhile, but I'll take some photos when I get there.

Right now, I'm trying to decide on a wiring strategy. I have two options:

1. Splice the C105 and C107 connectors into the Colorado wire harness
2. Almost completely replace most of the jeep chassis wiring and fuse box with the Colorado wiring and fuse box.

#2 might actually be easier, but I'm not sure yet.

Either way I've got to find a place to mount the PCM. I really wish Chevy mounted it to the engine like they do on the 4.2. The wiring design prefers the PCM to be located on the passenger side, but Jeep didn't start doing that until the TJ.
 

·
Registered
Joined
·
170 Posts
I took a look at radiator hose clearance and it seems okay. It might be awhile, but I'll take some photos when I get there.

Right now, I'm trying to decide on a wiring strategy. I have two options:

1. Splice the C105 and C107 connectors into the Colorado wire harness
2. Almost completely replace most of the jeep chassis wiring and fuse box with the Colorado wiring and fuse box.

#2 might actually be easier, but I'm not sure yet.

Either way I've got to find a place to mount the PCM. I really wish Chevy mounted it to the engine like they do on the 4.2. The wiring design prefers the PCM to be located on the passenger side, but Jeep didn't start doing that until the TJ.

I own a 2007 4.2 Trailblazer. I can say that while the computer looks good mounted to the engine, it is in fact a terrible idea. I had a 'no start' repair done to my harness a few years back and two evap wires also broke in the harness later. The wires are a small gauge and have no slack, so they seem to pull themselves apart with the engines movement. I think they could have done a better job of it, but they made the inner fender opposite the ECM a very busy place with the fuse box,power steering lines and upper control arm in close proximity to each other.



My personal goal is to keep the Jeep and MS3Pro as separate as possible.
 

·
Registered
Joined
·
42 Posts
Discussion Starter · #18 ·
Here is my wiring plan, splicing the Chevy wire harness into the C105 and C107 Connectors. In addition, I'll need to route several other wires into the cab. I might end up needing to drill another hole in the fire wall which isn't something I want to do.

I would love to add cruise control. We'll see how that pans out.
 

Attachments

·
Registered
Joined
·
42 Posts
Discussion Starter · #19 ·
I'm unable to join my Np233 Transfer case to the MA5/AR5 Transmission. The AR5 input seal is to large, and I can't find one that will work. Can I remove the seal and run without it, relying on the T-case to Transmission seal to stop the transmission from leaking? the opening is around 60mm, and the T-case input shaft is around 49mm.
 

·
Registered
Joined
·
170 Posts
Let me look into this for you. I still have the AR5 extension housing and a 231 input gear to get sizes from. If the seal is to large seal on the input gear diameter, it might be possible to sleeve over the input gear diameter to allow the AR5 seal to work. If it is possible , I can make what you need and get it to you. Another slim possibility, knowing the seal diameter and housing inside diameter....it may be possible to use an off the shelf lip seal.
 
1 - 20 of 48 Posts
Top