RavenMocker Posted January 12, 2014 Share Posted January 12, 2014 I bought this MJ for a Cummins project. I have no intention on using the 4BT nor the much heavier 6BT. Rather I own an engine that isn't very well known. But more about the engine later. First about the truck. It is an 1986 Comanche 2.5 with an AX5, D30, and D35. The transmission is shot as is the engine. The front axle has seen better days as well. The interior is red and I really hate red interior so that is going to change to maybe a grey one. It has the bench seat, the headliner has been stripped out, and hardly any of the lights work on the dash. The doors have grey panels with hand cranks for the windows. The bed has dents and some deep scratches in places. Body has broken plastic here and there, I would have to say that the truck as it sits now has seen better days and was begging me (or anyone else that cared about it) to buy it and bring her back to life. So that is what I will do. Now for the engine. The engine is a Cummins 6-AT 3.4 liter turbo diesel. It is about the same size and weight of the AMC 6. Fully dressed it weighs in at about 680 pounds. Now do not let the size fool you. I have this motor in a 4000 pound 4x4 vehicle now. It tows and runs just fine and I have yet to tune it for more power. Now being the engine is about the same size as the AMC 6 or a Chevy 235cid, or a Landcruiser 2F, it should fit within the engine bay with no issues. The oil pan is a rear sump and I am certain it will have no clearance problems. If it is does then I will just modify the oil pan for the application. The engine uses a universal GM bell housing bolt pattern. The Transmission I want to use is still up in the air. I have thought about using either an SM465, NV4500, or even an NV3500. But I am open to ideas. The Transfercase is also not decided. Something that would compliment the transmission as well as allow me to continue to use the factory shifter because well I kinda like the way it works. I will not be keeping the CAD system. That is going bye bye. The Axles.... Might stay with the OEM front axle and eliminate all the CAD crap and lock it into place so I don't have to worry about that system ever giving me issues. Extra stuff just means something else that I have to worry about breaking and/or troubleshooting. If it isn't on the truck, I don't have to worry about it. The D35 is getting dumped for something stronger. I might use an Aussie locker in the rear but also considering an ARB locker. Also would like to have 4 wheel disc brakes. Link to comment Share on other sites More sharing options...
carnuck Posted January 12, 2014 Share Posted January 12, 2014 http://www.ford-trucks.com/forums/947849-6at-cummins.html Link to comment Share on other sites More sharing options...
RavenMocker Posted January 12, 2014 Author Share Posted January 12, 2014 Ive read his build and I liked how he went about it. This was already in my current truck before the guy placed one in his ford. Actually have several years and miles on this conversion and it always starts and never misses a beat. :) Link to comment Share on other sites More sharing options...
onlyinajeep726 Posted January 12, 2014 Share Posted January 12, 2014 Well, I'm definitely subscribing to this... Never head of the 6at, but a diesel inline six that's small enough to fit in our MJs/XJs is something I'm interested in. What kind of MPG do you think you could get out of this? That's my main thing with a diesel swap if I were to ever do one. Torque and better MPG over octane. Link to comment Share on other sites More sharing options...
ilovemybike Posted January 12, 2014 Share Posted January 12, 2014 I'd go with the NV4500, an SM is so slow to shift. Should be a cool truck. Link to comment Share on other sites More sharing options...
RavenMocker Posted January 12, 2014 Author Share Posted January 12, 2014 Well, I'm definitely subscribing to this... Never head of the 6at, but a diesel inline six that's small enough to fit in our MJs/XJs is something I'm interested in. What kind of MPG do you think you could get out of this? That's my main thing with a diesel swap if I were to ever do one. Torque and better MPG over octane. I'm currently getting around 20mpg city and mid twenties highway. If you want something that is going to give you great fuel economy I would go with a VW 1.9 TDI or even a 1.9 TD as there is not an ecm. They are lite and easily tunable. I will be cleaning this motor up and tuning it for better fuel economy rather then power. Link to comment Share on other sites More sharing options...
RavenMocker Posted January 16, 2014 Author Share Posted January 16, 2014 I am also thinking about maybe using an automatic transmission this time around. Like a 700R4. I did however read up on using the AW4 and its Toyota counterpart in a Cummins 4BT application. Id rather like to stay away from computers and most electronics. Link to comment Share on other sites More sharing options...
RavenMocker Posted January 17, 2014 Author Share Posted January 17, 2014 The exhaust lets out on the drivers side of the engine bay. That is where the turbo is as well. So I may need to convert over to a passengers side pumpkin. If I do that then I am also going to consider beefing up the front frame and converting to front leaf springs. Link to comment Share on other sites More sharing options...
krustyballer16 Posted January 20, 2014 Share Posted January 20, 2014 http://comancheclub.com/topic/40407-cummins-b33-powered-mj-build/?hl=cummins this is my build... similar... Link to comment Share on other sites More sharing options...
RavenMocker Posted January 29, 2014 Author Share Posted January 29, 2014 http://comancheclub.com/topic/40407-cummins-b33-powered-mj-build/?hl=cummins this is my build... similar... Thanks thats helpful. I can't do anything yet until I get the engine pulled. And thats being a bit of a pain as I need to move the body someone else as I only have a single car garage down here and I live in a condo so I'm not allowed to park anything outside that doesn't run and is drivable. Right now I am thinking I might go with FZJ80 axles front and rear with oem electric lockers. I'm still going to a front leaf spring conversion and moving the transfer case to the passengers side, hence the front land cruiser axle. Ive also thought about transplanting the entire MJ only another truck frame thats already setup for the time being. Allowing me to drive it now and set up an actual proper conversion this summer. Are there any write ups on someone that has placed an MJ or XJ on a heavy duty truck frame? Link to comment Share on other sites More sharing options...
mnkyboy Posted January 31, 2014 Share Posted January 31, 2014 Sounds like a big project. just curious,have you looked into swapping an inline 6 into an 86? It takes a bit of modification to get one into an 86 since they never came with the I6, I imagine you are gonna have similar issues with your build. Link to comment Share on other sites More sharing options...
RavenMocker Posted February 10, 2014 Author Share Posted February 10, 2014 Sounds like a big project. just curious,have you looked into swapping an inline 6 into an 86? It takes a bit of modification to get one into an 86 since they never came with the I6, I imagine you are gonna have similar issues with your build. Ive measured things out and I think it will be ok. I will cut and modify the firewall and inner fenders if need be as well as anything else needed. I am confident that it will work. Link to comment Share on other sites More sharing options...
RavenMocker Posted February 17, 2014 Author Share Posted February 17, 2014 Well it looks like this project is in the process of chafing to another engine. The is a guy that wants to trade me an entire VW TDI for the engine. So if that happens then I will be going to a VW TDI which is smaller, liter, and creates more HP but and can still get 300+ ft-lbs of torque. Plus it simplifies things considerably with the front suspension and t-case/axle setup. Not to mention way better fuel economy. This Cummins 3.4 in my 4200lb truck went from 12mpg to lower/mid 20mpg. I would expect at least mid to upper 20's with the Cummins. But I would think the 1.9TDI would grant mid to upper thirties in the MJ if not more. I know my 2002 TDI was getting mid 40's in city and mid to upper 50's on the highway with an all time best of about 64mpg. Wish me luck. Link to comment Share on other sites More sharing options...
RavenMocker Posted May 1, 2015 Author Share Posted May 1, 2015 So its been a while and Ive finally come to the point where I can work on my MJ. I placed the Cummins 6AT into the engine bay just to get an idea of the weight and size of the engine in the bay and what mods will need done in order for the engine to fit properly. Here is what it looks like when sitting in the engine bay. I have decided to use the SM465 I have and currently seeking an NP205 t-case. I will be swapping out the front and rear axles for something stronger and going to a passengers side front pumpkin. The Cummins exhaust will be increased to a three inch straight pipe with no muffler. It is a turbo so the turbo acts as a muffler anyway. I also will be using a larger turbo, tuning the injection pump and using a better nozzle for the diesel injectors. Converting the engine to a front mounted intercooler. Other mods will include the conversion to an electric water pump, electric hydraulic pump for power steering, Hydroboost brakes, A/C, and HO Alternator. Dual fuel tanks for longer distance trips. Front Leaf spring conversion. Link to comment Share on other sites More sharing options...
Little jeep Posted May 1, 2015 Share Posted May 1, 2015 Sm465/np205 is a perfect combo. That's what I'm running Link to comment Share on other sites More sharing options...
RavenMocker Posted May 1, 2015 Author Share Posted May 1, 2015 Sm465/np205 is a perfect combo. That's what I'm running Have any pics of the install? Link to comment Share on other sites More sharing options...
DaveB26 Posted May 1, 2015 Share Posted May 1, 2015 Hey, its good to see that engine sitting in the truck. That thing is going to be sweet! I'm thinking that your going to want an overdrive maybe. But I guess it would depend on the new axles and gear ratio. But a Cummins in an MJ is awesome Link to comment Share on other sites More sharing options...
RavenMocker Posted May 3, 2015 Author Share Posted May 3, 2015 Today I got around to removing the drivers door and noticed the hinges have come unweld at the body. Guess I will be welding those and resealing them properly. I also removed the bench seat from the truck. Tomorrow if time allows from other projects I intend to remove as much of the remaining interior as possible. Then mark where I will be cutting the firewall and floor hump to accommodate the engine and SM465. Link to comment Share on other sites More sharing options...
RavenMocker Posted May 4, 2015 Author Share Posted May 4, 2015 Today I pulled the carpet, interior, most of the dash, seat belt, and such from the drivers side. I also looked at how much of the flooring was rusted out. Its not to bad on the rear half of the drivers side. Just some rust under the foot pedals and a hole punched through the flooring from the guy hitting something. I will remove what cancer is needed and replace with some sheet metal as its not a very big spot from what I can tell after testing the metal. Tomorrow I want to pull the passengers door, the rest of the interior/dash, and heating system. Then mark it where I want to cut the firewall and tunnel. I would like to set the engine back a few inches to help bring the center of gravity closer into the middle of the truck. The Cummins/SM465/NP205 combo isn't going to be lite. Push the truck into the driver way and hot soapy water time under the hood and inside the cab so I have clean surfaces to work with. I do have a few Q's that I thought I might pass by..... Using the passengers side drop t-case what axles would fit best under the MJ without sticking out to much? I do have a set of land cruiser axles Ive thought about using but then I would need to use the land cruiser t-case. They have 4.10's and disc brakes. Link to comment Share on other sites More sharing options...
RavenMocker Posted May 6, 2015 Author Share Posted May 6, 2015 Today I removed the dash. Link to comment Share on other sites More sharing options...
neohic Posted May 6, 2015 Share Posted May 6, 2015 I love these drivetrain swap threads. It's always little details, and little details, and little details... and then it all comes together! Nice job so far. :popcorn: Link to comment Share on other sites More sharing options...
RavenMocker Posted May 6, 2015 Author Share Posted May 6, 2015 So today I cut and removed the remainder of the exhaust pipe. Then pulled the Cummins out of the engine bay and set it aside. I drove out to me dads to get some of my tools and transmission jack that was left out at his place. So the truck is up on jacks stands and getting fitted with the SM465. Here is what is looks like as of today. This is the transmission with GM bell housings as it sits now. As you can see I was not able to push the transmission up into the tunnel due to it being to narrow. I will need to remove some of the tunnel so I can move the SM465 up six inches so that it fits properly for the Cummins 6AT. This is the inside of the truck... you can see how the transmission is lining up. And a shot to show how low the SM465 is sitting. The transfercase will be moved back about 12-14 inches. Link to comment Share on other sites More sharing options...
Little jeep Posted May 7, 2015 Share Posted May 7, 2015 Not yet I'll take some for ya Link to comment Share on other sites More sharing options...
RavenMocker Posted May 11, 2015 Author Share Posted May 11, 2015 Ive a herniated disc in my lower back thats keeping me from the project for now. Its driving my nuts not being able to get out and do something. My wife is watching me like a hawk. Hope to be back out in a few days and hope no more then a week. Link to comment Share on other sites More sharing options...
RavenMocker Posted May 15, 2015 Author Share Posted May 15, 2015 So Ive pulled everything out for the most part. Here is the firewall and some of the flooring. Link to comment Share on other sites More sharing options...
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