83 cj7 4.2 to 96 4.0 swap - JeepForum.com

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post #1 of 40 Old 09-06-2015, 06:57 AM Thread Starter
83threeper
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1983 CJ7 
 
Join Date: Aug 2015
Location: Crossett
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83 cj7 4.2 to 96 4.0 swap

Hello again gentlemen, I am looking to try and get a little advive and opinions on what route to take with the next step and perhaps biggest step of my cj7 build. Pretty much from the time I got the jeep I wanted to do a later model 4.0 swap in it. When I got it it was obvious the old 258 had seen better days, the thing looked like the little engine that could with all the blow by and leaked oil like the valdez. But regardless I it didn't stop me from putting a offenhouser 4 barrel intake, solit header and HEI distributor on it at no cost to me to just see if I could get it running a little better for awhile until I found my motor. But after these upgrades and much rewiring it evident that the 258 is all but dead.At least one cylinder must be dead.

But anyway, the big news is I found the donor for the 4.0. Its a 96 with 175,000 miles with all of the drivetrain good. It was rolled a few years back and has been sitting other than moved around a bit ever since. The motor sounds good and has good oil pressure.

My question is what are my options and what am I dealing with here as far as how big the job is. I have read quite a few threads on different 4.0 swaps and have heard quite a few different scenarios but haven't found much on all the options. Im kind of open to anything really. Original plan was to try and run the offenhouser 4 barrel intake and split header on the 4.0 but im not sure if that is possible or not. I would love to leave it fuel injected but I have read some on 95+ swaps being a headache where this is concerned. Again im open to any options really, i like the simplicity of carbing it but i love the idea of that fuel injection too. Thanks guys, and here is a snippet of the donor lol



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post #2 of 40 Old 09-06-2015, 07:16 AM
RubyCJ
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1986 CJ7 
 
Join Date: Nov 2010
Location: Waterford
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I've done 2 Cherokee transplants into CJ's. I used the ODB1 series (1992 - 1995) because they have the 4.0 HO motor and reasonably easy electronics. The 1996 motor is still okay but requires a little more electronic work and 2 Oxygen sensors, one on both sides of a catalectic converter. The 4.0 will bolt up to your CJ transmission but you will need a crank position sensor with notched harmonic balance wheel.
One of the transplants I did I used the Cherokee transmission so I could keep the crank position sensor mounter on the bell housing. Need to get an adapter to connect to my D300 transfer case.
Probably the most time consuming was morphing the two wiring packages together so the newer electronics controlled the motor and kept the CJ starting and dash controls.
Definitely love the added power and hill climbing with the ported fuel injection.
Good Luck !
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post #3 of 40 Old 09-06-2015, 07:30 AM Thread Starter
83threeper
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1983 CJ7 
 
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Quote:
Originally Posted by RubyCJ View Post
I've done 2 Cherokee transplants into CJ's. I used the ODB1 series (1992 - 1995) because they have the 4.0 HO motor and reasonably easy electronics. The 1996 motor is still okay but requires a little more electronic work and 2 Oxygen sensors, one on both sides of a catalectic converter. The 4.0 will bolt up to your CJ transmission but you will need a crank position sensor with notched harmonic balance wheel.
One of the transplants I did I used the Cherokee transmission so I could keep the crank position sensor mounter on the bell housing. Need to get an adapter to connect to my D300 transfer case.
Probably the most time consuming was morphing the two wiring packages together so the newer electronics controlled the motor and kept the CJ starting and dash controls.
Definitely love the added power and hill climbing with the ported fuel injection.
Good Luck !
I love the idea of leaving it fuel injected and I have also seen and heard about the crank position sensor. Yet another part of me says run a carb on it and not worry about any of that lol. Basicallyjust swap the motor into my jeep and be done other than the fuel pump and whatever issue I may run into with a intake. Either i need to buy a later model 4 barrel intake for a 4.0 or if my offenhouser 258 intake can be made to work. If I have to sell my 258 intake or trash the thing it doesn't really matter to me because it didn't cost me anything. I also like the simplicity of running a carb.

Also if I do run a carb, does anyone know the recommended cfm for a 4.0 and what is a good carb to look into?
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post #4 of 40 Old 09-06-2015, 03:51 PM Thread Starter
83threeper
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I guess a big question on this is if I decide to go efi will i need a 5 speed ecm? The donor jeep is a 2 wheel drive auto.
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post #5 of 40 Old 09-06-2015, 04:02 PM
orange150
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1982 CJ8 
 
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I've read the only thing not having the proper ecm to match your trans will do is throw a code. So if you're not running a check engine light you should be fine.

'82 CJ-8
258/AX15/D300
OME YJ 2.5"/31s
D30/D44/3.73s/Truetracs
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post #6 of 40 Old 09-06-2015, 04:13 PM Thread Starter
83threeper
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Quote:
Originally Posted by orange150 View Post
I've read the only thing not having the proper ecm to match your trans will do is throw a code. So if you're not running a check engine light you should be fine.
Yeah, no check engine light so thats a plus.
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post #7 of 40 Old 09-06-2015, 07:53 PM
Bgeddes
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Are you planning on rebuilding the 4.0 before install? If so you have enough goodies to build a budget stroker.

Also, two friends have tried the split header and both went back to a 6-1...YMMV

'00 XJ Classic > Stock DD
'88 Grand Waggy - Bone stock pseudo-barnfind
'78 CJ5 - Under minor rehab
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post #8 of 40 Old 09-06-2015, 09:17 PM Thread Starter
83threeper
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Quote:
Originally Posted by Bgeddes View Post
Are you planning on rebuilding the 4.0 before install? If so you have enough goodies to build a budget stroker.

Also, two friends have tried the split header and both went back to a 6-1...YMMV
Wasn't planning on it bud. Would be cool to do one day though.

Yeah im seriously thinking about getting rid of the split header. I can't get it to seal off anyway, bad exhaust leak in the center of the head.
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post #9 of 40 Old 09-06-2015, 10:01 PM
SLO_Ken
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Location: California
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If you decide to keep the fuel injection, I recommend getting the diagnostic port connected and functioning. This way you'll be able to read codes to help diagnose issues when they crop up.

California 4.0 OBDII Engine Swap
http://www.jeepforum.com/forum/f8/california-4-0-obdii-swap-1530716/
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post #10 of 40 Old 09-07-2015, 04:02 AM Thread Starter
83threeper
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Quote:
Originally Posted by SLO_Ken View Post
If you decide to keep the fuel injection, I recommend getting the diagnostic port connected and functioning. This way you'll be able to read codes to help diagnose issues when they crop up.
Oh definitely I would say as well.
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post #11 of 40 Old 09-07-2015, 05:17 AM
Mike Romain
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I just put the carb intake and distributor on my 4.0. Had to use the 4.0 exhaust. My old BBD runs it just fine, giving great gas mileage so basically any carb that can handle the 258, 4.2 can do the 4.0. I also stayed V-belt by swapping the front parts over. My pilot bushing needed a little rework, OD was a big big, but I hear you can buy the correct size. Had a muffler shop join the 4.0 header to the CJ pipe.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG AT's, 'glass nose to tail in '00, 'New' frame,wires and plumbing in '09. Carter BBD Carbed 4.0 HO in '10.
89 YJ Renegade. BBD Carbed 4.0 HO. Locked front and rear with 33x9.5 BFG AT's
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post #12 of 40 Old 09-07-2015, 05:52 AM
yellowjeep79
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I swapped a '94 XJ 4.0 into my '79, and I really love the fuel injection. This thing never stalls on angles now, where my old 4,2 with Weber would occasionally and then would be hard to restart. Adding the crank position sensor was pretty straight forward and the VSS to the X-case was easy. The wiring was a *****, but with the factory service manual it was do-able for the '94. You're into the OBD II, so I can't give any advice there. I added a toggle switch for the neutral safety switch (mine donor was an automatic) and kept the diagnostic port under the hood and added an idiot light on my dash. I used the air conditioning compressor for on board air, so it is constantly throwing a code telling me my A/C compressor is bad. That my means my idiot light is always on. My wife says the idiot light is on for other reasons. All in all, it was way worth the trouble.

'48 CJ2A, '56 DJ3A, '79 CJ7, '04 TJ and two of them actually run!
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post #13 of 40 Old 09-07-2015, 06:43 AM Thread Starter
83threeper
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Quote:
Originally Posted by SLO_Ken View Post
If you decide to keep the fuel injection, I recommend getting the diagnostic port connected and functioning. This way you'll be able to read codes to help diagnose issues when they crop up.
I just more or less read your build thread and I think im basically sold on running it fuel injected. You went threw hell with the Cali. emissions stuff man! I commend you for your patience on that lol. But yeah, your build thread is very helpful. I will be referring back to it quite often im sure.
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post #14 of 40 Old 09-07-2015, 06:44 AM Thread Starter
83threeper
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Quote:
Originally Posted by Mike Romain View Post
I just put the carb intake and distributor on my 4.0. Had to use the 4.0 exhaust. My old BBD runs it just fine, giving great gas mileage so basically any carb that can handle the 258, 4.2 can do the 4.0. I also stayed V-belt by swapping the front parts over. My pilot bushing needed a little rework, OD was a big big, but I hear you can buy the correct size. Had a muffler shop join the 4.0 header to the CJ pipe.
Hey its good to see someone actually done this. Seems to be unheard of. Its still not thrown out for me but I am seriously leaning towards the efi.
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post #15 of 40 Old 09-07-2015, 06:47 AM Thread Starter
83threeper
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Quote:
Originally Posted by yellowjeep79 View Post
I swapped a '94 XJ 4.0 into my '79, and I really love the fuel injection. This thing never stalls on angles now, where my old 4,2 with Weber would occasionally and then would be hard to restart. Adding the crank position sensor was pretty straight forward and the VSS to the X-case was easy. The wiring was a *****, but with the factory service manual it was do-able for the '94. You're into the OBD II, so I can't give any advice there. I added a toggle switch for the neutral safety switch (mine donor was an automatic) and kept the diagnostic port under the hood and added an idiot light on my dash. I used the air conditioning compressor for on board air, so it is constantly throwing a code telling me my A/C compressor is bad. That my means my idiot light is always on. My wife says the idiot light is on for other reasons. All in all, it was way worth the trouble.
Ive heard a lot of things about them stalling on angles. The wiring is sorta scary ill admit but im not sure ive ever met anyone that wasn't a little shaky on a project like this lol. The good thing is i have the entire xj to get anything i need off it.
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