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repowering cj6

Discussion in 'Intermediate CJ-5/6/7/8' started by jeep6275, Feb 27, 2011.

  1. Feb 27, 2011
    jeep6275

    jeep6275 Member

    south east iowa
    Joined:
    Feb 14, 2007
    Messages:
    67
    hey guys,

    i hope this is the correct area for this post if not just move it.

    i have a 74 cj6 that i am wanting to swap a fuel injected 4.0 into. it seems for what i want it would be best for me to swap the engine and transmission. i have been looking for cherokees with the 4.0 and aw4 but they are few and far between. but in my area grand cherokees are very common and cheap for some reason. from the threads i have read on here it sounds like the ideal transmission is the aw4, but the grands i find all have the mopar transmission in them. basically i have been unable to find grands older than 95. today for example i found a low mileage 95 grand for 300 bucks.

    so after all of that my quesion is, what is wrong with swapping a 4.0 with a mopar tranny into my cj? i am lucky if i drive it a few thousand miles a year so i doubt the transmission will ever get wore out. are their any companys that offer aftermarket support, like wiring harness and adapters for these transmissions?? i have found alot of info about the aw4 but not so much about the mopar transmissions.

    all thoughts and opinions are appreciated

    jeep
     
  2. Feb 27, 2011
    zila

    zila I throw poop

    Rock Springs,...
    Joined:
    Oct 6, 2003
    Messages:
    1,201
    All I can say is that a guy here put a V8 engine out of a grand in his CJ.. Don't know what he did tranny wise.. He did have to install a regulator and pressure switch in the fuel system though.. Haven't seen him for quite a while so I can't ask him for ya.. His was a 90's model??
     
  3. Feb 27, 2011
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
    Messages:
    12,529
    The AW-4 is a much better transmission if you can source one. The early, I think it's the 42re? transmission has a reputation for issues. Not sure what years however. A co-worker specializes in these and has stated many times it's not the best transmission.

    Another thing to think of, what transfer case are you planning on using? IIRC the Grands were full time 4x4 and have the front output of the transfer case on the wrong side to use your front axle. You can retrofit a Dana 300 transfer case to them but depending on if the transmission is a 21 or 23 spline output shaft you may have to get a custom input shaft for the 300. Stock the 300 is 23 spline.
     
  4. Feb 27, 2011
    timgr

    timgr We stand on the shoulders of giants. 2022 Sponsor

    Medford Mass USA
    Joined:
    Aug 10, 2003
    Messages:
    23,596
    Supposedly the earlier modesl (86-87) used the A999 - I would not think that's any more problematic than the AW-4. The AW-4 has an excellent reputation though. The Grand Cherokee used the 42RE (A500) at first, and I recall that it's troublesome.

    I find it hard to believe that you cannot find a dononr Cherokee with a 4.0L/AW4 combo. Jeep made a gazillion of them, and they run a long time but don't hold up against rust that well.
     
  5. Feb 27, 2011
    jeep6275

    jeep6275 Member

    south east iowa
    Joined:
    Feb 14, 2007
    Messages:
    67
    i agree that it seems odd that i cannot find any xj's. ive owned one and it seems like everyone i know has as well. its probably because i am looking for them!!!

    anyway i went and looked at the grand. it was a pile. 185,000 miles, cracked exhaust manifold, rod knock, and something was wrong with one of the accesories. (it knocked also) so it was a lost cause

    ill keep looking i am not in a big hurry, my current engine runs it just seeps from the rear main seal and a frost plug leaks a little.

    as far as the transfer case question, my plan is to find a 4.0 with the aw4 and np231, then just go snag a np231c from an s10 or similar chevy product. this way i will have the output on the passenger side.

    hope it all goes together as well as i think it will!

    jeep
     
  6. Feb 28, 2011
    pathkiller

    pathkiller Member

    Lorton, VA
    Joined:
    Apr 17, 2005
    Messages:
    878
    I have a 4.0L (now stroked to 4.6L) with an AX15 manual 5-speed mated to a Dana 300 in my CJ8. It's a great combination. I switched it over to Painless' "Perfect" Engine Management System last year, which uses a tunable Delphi MEFI 4 computer instead of the stock MOPAR unit (my MOPOR ECU went bad, and I had an enormous amount of issues with the stock setup). Mine is from a 97 XJ, which is OBD2 and has a lot more sensors, thus making it a more difficult swap.

    If you want the factory computer controlled transmission (AW4) you have to use the factory ECU and the TCU that goes with it. This swap is on the deep end of complicated. The 4.0L swap forum at cjoffroad.com was a great resource, but that board has been down for a long time and no one's sure if it's coming back. Regardless, these swaps have been well documented, there's a lot of info out there on them.
     
  7. Feb 28, 2011
    jeep6275

    jeep6275 Member

    south east iowa
    Joined:
    Feb 14, 2007
    Messages:
    67
    thanks for the info! i have done engine and drivetrain swaps before, i have even swapped the tbi from a 4.3 gm v6 onto a buick 3.8 v6. it does appear that this swap will be more technically challenging but it seems like the info/resources are endless so hopefully i will come out successful in the end!!
     
  8. Feb 28, 2011
    nickmil

    nickmil In mothballs.

    Happy Valley, OR
    Joined:
    Sep 23, 2002
    Messages:
    12,529
    Be aware most late model 231C's from GM's were driver's side front outputs.
     
  9. Feb 28, 2011
    Dummy

    Dummy I kick hippies

    Escondido, CA
    Joined:
    Dec 5, 2004
    Messages:
    646
    They're also 27-spline. You'll need a 23-spline input gear from a Jeep/Dodge NP231.
     
  10. Feb 28, 2011
    78-5r

    78-5r Member

    Belleview, FL
    Joined:
    Mar 18, 2010
    Messages:
    68
    I would consider using a D-300 if you need it to be P-drop. I believe they are fairly easy to put on an AW4.

    As for the difficulty of the swap...as long as you use the COMPLETE harness etc from the donor vehicle and the ECU and TCU it really isn't too bad. We've swapped one into a manual MJ and also into a manual XJ.

    If you have not done so yet go to NAXJA.org and do some research on the manual shifting of the AW4. It is pretty neat what some of the folks over there have been able to do with it. All the way to full manual shifting and paddles on steering wheel to do so (read rally style).

    Also check on IFSJA.org. At least one person over there was putting an AW4 behind a 360 in a grand wagoneer. That's putting a computer controlled tranny in a non computered rig...lots more good info there.

    Also if you don't need an over drive don't overlook the TF-727. You can put a D-300 behind one of those as well (it takes some work but it's not to hard...I had one in a YJ) the front DS to trans pan is the only real issue there. And the CPS on the 4.0L can be placed (using a kit) on the front of the engine. A good friend of mine has done this in his YJ with the stock 4.0L and a 727. Since it requires no wiring and the only real adaptation is the CPS on the engine...it is not a tough swap other than to actually do it.

    yet another good site is to google Stu Olson...he has (or had) writeups about putting an AW4 into a TJ...which is probably more difficult than using an entire engine/trans/harness setup from a single donor rig.
    I am not sure how far you are willing to travel for the donor rig but there are generally at least a few OBDI ('91-95ish) XJ in the yards here in Ocala, FL and in the last 6 months I have seen 4 late models as well. All 4.0L autos. You may be right...you're having trouble finding one near you because you want one!
     
  11. Feb 28, 2011
    jeep6275

    jeep6275 Member

    south east iowa
    Joined:
    Feb 14, 2007
    Messages:
    67
    thanks for all the info guys!!
     
  12. Feb 28, 2011
    jeep6275

    jeep6275 Member

    south east iowa
    Joined:
    Feb 14, 2007
    Messages:
    67
    can i use the input gear out of the xj tcase?

    now you guys have me thinking..... does anyone have a better idea? my jeep has the 304 and t14 (?) and dana 20. the rear main seal and one frost plug are leaking. not bad but enough to get me thinking about something else.

    my first thought was to swap in the xj setup, i knew the tcase output was on the wrong side but thought a chevy tcase would work.. it sounds like it wont.

    my thought with the 4.0 was that i would have fuel injection, more power than the 304 and an overdrive transmission. when i checked into rebuilding my 304 i got prices close to 2000 bucks. keep in mind i have never rebuilt an engine, so i was just dropping off a long block and picking up the same.


    in the last couple yrs i have seen many xjs with just over 100000 miles for a thousand bucks, from everything i have read and seen with this setup that is just getting broke in! i figured i could buy the jeep take out what i need, part out the rest and get something for my engine trannny and tcase. then hall the scrap steel to the scrap yard. i was guessing with everything included, i could do it for the cost of the 304 rebuild. i wanted to swap the aw4 in because it seemed easier/cheaper than the manual tranny, or trying to adapt the 4.0 to my existing 3 spd that always seems to have the incorrect gear.

    any better ideas guys? shoot holes in this and give me some options.

    thanks in advance.

    jeep
     
  13. Mar 1, 2011
    78-5r

    78-5r Member

    Belleview, FL
    Joined:
    Mar 18, 2010
    Messages:
    68
    The easiest thing is if your engine is running well ...pull it...replace all the freeze plugs and do the rear main, oil pan gasket, valve cover gaskets, and anything else than can leak oil and water. That's a weekend project if you have the tools and time. This would probably only cost you $100-200 in parts if that and then the time it will take to do the work.

    If you want more power but still fairly simple and not as pricey just find a waggy with a 360 and swap that in. It should just about be 100% bolt in.

    As for the power to power of a 304 vs a 4.0L...other than the possible better driveability of the MPI 4.0L it's not a big difference. I currently own and drive regularly a 4.0L XJ (have owned MANY) and my CJ-5 with a 304. Both rigs weigh about the same. and one has 30" and the other 31" tires. The XJ will crank up and go NOW...whereareas my CJ takes about 5-10 minutes to really warm up..longer on colder days. ***I know part of that is the carb not being adjusted quite right as it runs a little rich to me***.

    Power wise...if I had a 5 spd or an auto behind my 304 I think it could hang with the 4.0L fairly easily...maybe even beat it stoplight to stoplight but that's it. Past that I think they are about the same.

    A group of us had a big debate on another forum with a guy who was wanting to pull out a decent 4.0L and swap in a 304 (the reverse of what you are thinking of)...we tried to talk him into either gearing the axles correctly for his tire size OR swapping in a 360. He swore all up and down he could beat the 4.0 with a 304. Then...after swapping in the 304 he decided he wants a much higher HP engine. He said he had dyno numbers that prove the 304 beat the 4.0L but then I come to find out he did some massaging on the motor and it wasn't a true stock for stock comparison.

    I love my 304...but I have decided that once it has been put to pasture...unless a good 304 falls in my lap I will seek out a 360 or do a 4.0L swap. Thankfully I only have 85,000 miles on mine and God willing I'll put twice that on it before having any major issues and before I have to decide which route to take.
     
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