banjobill80 Posted November 7, 2009 Share Posted November 7, 2009 Hi all was hoping to get some thoughts on what it would take to swap a 4.0L in the place of an 2.8L GM v6. Of course I realize the tranny and all will have to go. I have a 86 mj 2.8 5 speed 4x4 locked motor. Not having much luck finding a good used 3.1/3.4 everything is worn out So the question is If I were to get a donor cherokee with a 4.0 auto. What kind of headaches might one expect with wiring exc. Any one done something all these lines?? I guess I figure that if I'm going to spend the money to total rebuild and engine it my as well have more power then the 2.8 had one in a mj a long time ago with an auto trans what a dog Thanks for your thoughts Bill.. NE Ohio :typing: Link to comment Share on other sites More sharing options...
WBKrazy Posted November 7, 2009 Share Posted November 7, 2009 the best way to do the swap is pick up a complete donor and strip out everything you need, however the firewall on the '86 is where you'll have issues... the 4.0 wasn't available in the xj/mj till '87, and they had to redesign the firewall to make it fit in there... there's people in here who have done it i'm sure tho... Link to comment Share on other sites More sharing options...
banjobill80 Posted November 7, 2009 Author Share Posted November 7, 2009 Thanks good to know I look forward to hearing how/if guys have gotten around that. I may just have to rebuild the 2.8 then but at the very least will stroke it. Bill.. Link to comment Share on other sites More sharing options...
Pete M Posted November 7, 2009 Share Posted November 7, 2009 don't touch that 2.8. Buy a 3.4 and rebuild it. The castings and inner oil passages are vastly superior in the newer blocks. :thumbsup: Link to comment Share on other sites More sharing options...
freakjeep93 Posted November 7, 2009 Share Posted November 7, 2009 we can make er fit by the firewall always remember the BFH works for me Link to comment Share on other sites More sharing options...
mvusse Posted November 7, 2009 Share Posted November 7, 2009 Fire wall modification is supposedly easy enough: just a few swings with a BFH, as the extra needed clearance is pretty small. The 2.8V6 is a gas guzzler that produces less hp than the 2.5l straight 4. I say get a 4.0 Cherokee, and swap everything over: engine/trans/tfer case/wiring harness/computer. I've been lucky, as both my MJ and my XJ have a 4.0, so have no personal experience. But there are a number on people on here who have done a 4.0 swap. Another option is to swap in a 3.4V6 out of a fourth generation Camaro or Firebird. Same exact block, keep your current transmission. JeepcoMJ swapped in a 3800 out of something, but it makes too much torque and was eating transmissions for breakfast, lunch and supper. Link to comment Share on other sites More sharing options...
banjobill80 Posted November 7, 2009 Author Share Posted November 7, 2009 Thanks Guys wouldn't a 4th gen engine be a FRW there by have the starter,oil filter and everything else in the wrong places? I also think the motor mounts would be completely different as the Front Wheel Drives don't use mounts on the sides of the motors but rather on the front and back with the big dog bone support up in front? Link to comment Share on other sites More sharing options...
Automan2164 Posted November 7, 2009 Share Posted November 7, 2009 Looks like you got the one off ebay... Good looking truck. I would say to just go ahead and get a XJ donor and go 4.0. I have the same plow sitting in the garage. Hey, you aren't getting rid of that rollbar by chance would you? I would be interested. I'll shoot you a PM. Rob L. Link to comment Share on other sites More sharing options...
banjobill80 Posted November 7, 2009 Author Share Posted November 7, 2009 Yeah got her off ebay about 2 weeks ago drove about 320 miles for it and was pleasently surprized when I got there. The truck is unbeliveable underneith the plow has hit something solid and bent the front of the unibody a bit but did not disturd the sway bar or anything and like I said befor the motor is locked tight. It had sit on a shelf Yeah a shelf in a big auction house for about 10 yrs some sort of estate thing I guess. I do have some surfase rust under the rubber matt but no holes. plan on compleatly guting interior and blasting everything and go from there. Looking forward to this build Bill.. Link to comment Share on other sites More sharing options...
Eagle Posted November 7, 2009 Share Posted November 7, 2009 Thanks Guys wouldn't a 4th gen engine be a FRW there by have the starter,oil filter and everything else in the wrong places? I also think the motor mounts would be completely different as the Front Wheel Drives don't use mounts on the sides of the motors but rather on the front and back with the big dog bone support up in front? Camaro and Firebird. Also available from GM as a crate engine. Link to comment Share on other sites More sharing options...
JeepcoMJ Posted November 8, 2009 Share Posted November 8, 2009 the problem with the motor I used (series II buick 3800 out of a 96 camaro) was that I retained the factory ax5 5 speed. i should have gone with an ax15 and dodge dakota bellhousing from the get-go. I also probably shouldn't drive it like I'm a nascar driver... anyways, to put a 4.0 in you will need to drill all the spot welds out of the 2.8 radiator supports (behind the headlights) as well as the front frame crossmember, and you will need to do the same on the donor xj or mj and put those supports into the 86. this is necessary, not optional for the swap...you just won't be able to put the 4.0 radiator in otherwise. you'll also need an 87+ hood, as the hood latches are completely different. there may or may not be any firewall differences. evidence has shown that later in the 86 production, they were already gearing up for the 4.0. it's a few hits on the lower areas of the transmission humps. get the whole donor if you can. as far as the 3.4 swap is concerned, it will be easier and you can gain fuel injection by doing this swap. you're looking for a 91-95 camaro or firebird to do this swap. Link to comment Share on other sites More sharing options...
banjobill80 Posted November 10, 2009 Author Share Posted November 10, 2009 So I found a 3.4 in a 94 camaro. It has a auto tranny will this pose any problems being I have a 5 speed? I think I will also go with an edelbrock intake with a holly carb just to avoid all the electric/computer issues. Any thoughts or warnings out there? Thanks.. Link to comment Share on other sites More sharing options...
86FUBAR Posted November 10, 2009 Share Posted November 10, 2009 So I found a 3.4 in a 94 camero. It has a auto tranny will this posse any proublems being I have a 5 speed? I think I will also go with an eldabrook intake with a holly carb just to avoid all the electric/computer isues. Any thoughts or warnings out there? Thanks.. That will work perfect , and no it don't matter that its an auto . i used a a 94 auto 3.4 in my 5speed manch and it worked fine and the eddy intake but i kept all the stock electronics along with the carb here is my build thread , theres some pics and info on page 2 viewtopic.php?f=7&t=5484&start=30 Link to comment Share on other sites More sharing options...
Eagle Posted November 10, 2009 Share Posted November 10, 2009 So I found a 3.4 in a 94 camero. It has a auto tranny will this posse any proublems being I have a 5 speed? I think I will also go with an eldabrook intake with a holly carb just to avoid all the electric/computer isues. Any thoughts or warnings out there? Thanks.. The only thing to watch out for is that the 2.8L wasn't a well-balanced engine, so the flywheel has an eccentric balance weight on one side. When they came out with the 3.4L they did a better job balancing the engine internally, so the flywheel didn't need to be externally balanced. So you can use your flywheel but you'll need to send it to a machine shop to have it neutral balanced. Link to comment Share on other sites More sharing options...
Tri_X_Troll Posted November 11, 2009 Share Posted November 11, 2009 So the ax-15 with the dakota bellhousing will bolt up to the 3.4? What kind of dakota does the bellhousing need to come out of? I think that I read somewhere that the flywheel out of the donor camaro can be used to avoid balancing the manche one. Link to comment Share on other sites More sharing options...
Eagle Posted November 11, 2009 Share Posted November 11, 2009 So the ax-15 with the dakota bellhousing will bolt up to the 3.4? What kind of dakota does the bellhousing need to come out of? I think that I read somewhere that the flywheel out of the donor camaro can be used to avoid balancing the manche one. The bellhousing needs to come from a 2.5L 4-cylinder Dakota. Dunno on the flywheel. I was going to say it definitely wouldn't work, then I remembered that the 2.8L doesn't use a CPS. So ... maybe. Link to comment Share on other sites More sharing options...
86FUBAR Posted November 11, 2009 Share Posted November 11, 2009 U could use the flywheel out of a newer s10 as they were neutraly balanced here is a thread on this subject http://60degreev6.com/forum/f109/3-4-sw ... 564/page12 Link to comment Share on other sites More sharing options...
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