715 engine swap

[Robert Denton]

Hi Guys,
Do any of you know if the 6.2 diesel swaps into the 715 easily, maybe as easy as a 350 chevy maybe not. Same Adapter? I'm only considering it if it swaps in relatively the same as the 350 gas motor. Thanks in advance.

 

[kevin-m1008]

It should be as easy as the 350 or the 454 as was my case. but what plans do you have for the stock gearing? or what is your use of the truck?

Things to think about:
1. radiator size,
2. gearing 5:87 means your top speed will be low
3. What shape is your x-fer case. most of the stock ones overheat at highway speeds when driving longer then a hour


These are great trucks and wen I sell my 454 I have a 4bt that will replace it.

Have fun!

 

[Barrman]

As written above. If you can get a SBC or BBC in there, a 6.2/6.5 will fit and bolt up the same way. As also mentioned above. Gearing is going to be a problem.

I have a NV4500 in my M715 with the Michelin 11.00-16 tires. 5th gear 2000 rpm is 52 mph. Which just happens to be as fast as I can go because the stock NP200 will overheat on long runs at any speed above that. If that is all the speed you need or want, have at it. If you want more speed, think 4.56 gears which will give you another 5-8 mph before the tcase stops you again. The NP200 needs to stay below 2500 drive shaft rpm.

Or, a NP202 or NP 205 swap. But, then the 6.2 limit of 2200 rpm for a long engine life will cap your top speed. So, you are back to axles swaping or going below 55-60 mph.

I say axle swapping because by the time money is spent to get 4.56 gears in the stock axles, you could have been partly through a CUCV D60.14B swap. That swap gives you disc brakes in the front, a locker in the rear, much heavier parts and if you are using the stock M715 rear springs, you have to put on rear disc brakes. All this makes it so the truck will stop and go.

Speed cost money, how fast do you want to go?

 

[Robert Denton]

response to 4BT

Hey,
I love nothing more than the idea of the 4bt, but I'm told it's a big undertaking, with the cost of engine, and all the mods necessary to make the fit. If somebody wrote a step by step book for the 4BT conversion with clear photos for some of the more popular trucks they could probably charge $75.00 a copy or more. Make them separate books for each truck. Then they could get together with a fabricator who could make the essential switch over parts if any and they could release the catalog of fabricated parts with the book on How-to do it. The fabricator could of course sell other items that he makes in that catalog.
I'd probably buy that book just to see how involved it is. I know there's a lot of free help on the net, but I like having that old book in my hands so I can enjoy the job and the learning more. That's why I've gotten the manuals for every army truck I've ever owned.
Right now I'm looking for a good 84-86 lower mileage CUCV Pickup or possibly ambulance or Maint. Truck and I'll get that manual as well.
You Know what you've done right. You've made me start thinking about the 4BT
again instead of the 6.2 liter.
The stock engine runs ok for now so I'll probably keep looking for that 84-86
M1008 for longer trips and just keep the 715 on shorter runs.

thanks.

 

[Barrman]

PM or Email Mcinfantry. He build a M715 exactly as you described about 8 years ago. He has since sold it, done the same to a few other vehicles and is redoing one now.

Mounting a 4Bt is easy. So is a 6Bt actually. The 6Bt just has a little too much length for the M715. 4Bt is not a fitment problem at all. When you look for a 4BT. Look for one with a Chevy bellhousing pattern rear plate and the inline IP. Most of those engines either have a TH400 or a NV4500 bolted to them already.

Now, a M1008 or any CUCV truck donor with the married 208 or married 205 is an easy weekend swap if you do engine/transmission and tcase as a unit. easy to do with plenty of spare cheap parts available.

 

[spicergear]

I put a 6.2 in an M715 with an NV4500 (Chevy 2wd style) then swapped out the NP200 for a Dodge fine spline NP205. 6.2 is slightly larger than a small block and not as big as the BBC. I have put all mentioned into M715's and they all fit well. I don't know what you're doing for engine mounts but I simple used the factory 6cly mount and made a plate of 3/8" steel that had those two bolt mounts (incorporating the factory rubber mount -JEEP) and then the 3 hole block mount from the Chevy. IIRC...you'll want one of the two jeep mount bolts to overlap into the chevy's 3 hole pattern. That should put you about dead on for firewall clearance. Those trucks are great platforms for engine swaps! Over revved and dropped valves of the factory inlines help too.

 

[bcowanwheels]

THIS IS A JOKE......" Mounting a 4Bt is easy ". HOW ABOUT ALL THE PLUMBING & COOLING , EXHAUST, CLUTCH LINKAGE, DIFF CLEARENCE, FUEL SYSTEM, AIR FILTER ASSY., BATTERY, THROTTLE LINKAGE, ELECTRIC WIPERS ON AND ON IT GOES........ AND BY THE WAY A 6.2 IS A JUNK ENGINE. ITS WHY THEY WENT TO 6.5. DO YOURSELF A FAVOR AND PUT A SBC IN THERE IN A WEEKEND AND BE DONE WITH IT IMO AND I,VE DONE THEM ALL.

 

[oilcan]

The 6.2 is a better motor than some people give it credit for. And don't get sucked in by the "this is the way I did it, so you're stupid if you don't do it the same way" crowd. That attitude does help keep the price of a decent 6.2 down, though.

My setup is a 6.2 n/a, SM465 4 sp, stock t-case and axles. It's down for maintenance right now, but the combination has worked great for me. My t-case is one of the few that doesn't seem to overheat at speed.

 

[spicergear]

Mine ran and worked very well in the M715 with the NV4500's decent OD and even with the stock deep axle gearing. One thing...this set up is tough to round up if you don't have donor parts and have to find them individually. A 6.2 manual flywheel isn't the easiest thing to find. The drive is VERY mechanical feeling. When you're in the pedal you move forward and with the deep axle gearing you move forward NOW. Same with decelerating...you lift and it slows fast. I never had it loaded but it did seem to work well while I had it.

 

[Barrman]

BOB,
All the stuff you mentioned has to be done no matter what engine is swapped in. That stuff is the "given" for a motor swap. I last saw Lee's 4Bt truck in your shop back in 2006. So we both know that a 4BT is a simple engine to fit into a M715. Sure it has to be plumbed and wired, but so does everything else.

I drove my stock M715 into my shop on a Friday evening back in 2005 and drove it to work the following Monday with a BBC/NV4500. I used the "Spicer plates" that Tom described and have been named after him in the M715 community to mount the engine. Easy swap.

I have put a SBC with a 3053A 5 speed behind it in a 715 and it was just a matter of collecting the parts and bolting it together. Spicer plates used again. Easy swap except for the rear transmission mount and clutch linkage needing some thinking. Still pretty easy.

I have seen Tom's 6.2/NV4500 truck and wheeled a week with Adam and his 6.2 truck. His 6.2 did better on the trails than my carburated 396.

I am building a 6BT M715 currently for Sermis in my class. The engine fits, but not by much. Every part of the swap requires modification to something. Add in the spring over open knuckle CUCV D60 up front and shackle flip disc brake 14 bolt in the rear and things get complicated.

My point is what I was trying to convey in my first post yesterday. There are unlimited options to what will fit a M715. Ranging from cheap and easy as engine swaps go to expensive and easy to expensive and hard. However, thinking 15 steps ahead and intended useage is needed or the cost will sky rocket on you.

Now, as far as the 6.2 goes. Yep, they don't have the power potential of a Cummins. They don't have the reputation of a Cummins either. They also don't have the price tag of a Cummins. They do have the ability to go just about anyplace a SBc was mounted, bolt up to common parts without a several thousand dollar adaptor being bought and if kept below 2500 rpm will last many years. Those many years will probably include a $500 IP rebuild. Which will maybe make the total investment in the 6.2 $1000 or so. A Cummins can't do that.

 

[spicergear]

Well put-

Yeah...putting a rear mount on the 3053A's can be a bugger! Tim, if you're ever around that 6.2 truck I put together again, check out the NP205's driver side mount. Used the PTO port since there wasn't going to be a 10K Garwood under the bed of that too. Wow was that an easy job mounting that 205 case then!

 

[Barrman]

You mean the one in the picture below? I remember looking at it because Colton tried to stand up and wacked his head on the frame. He had a knot on his head for days after that. I was so impressed with how easy that was. That I came home and built a pto cover out of 1/4" steel. I saw it sitting on the work bench the other day.

That trip kind of ties into this thread in another way. We left your place, drove all night and met BOB at his place in TN the next morning. He had Lee's 4Bt truck in there for some tunning the then owner wanted, a bunch of 4BT's sitting around and stuff that we talked about. Then we went to AB Linn for parts in NC. Later the next night we met up with Snuffy in AL to pick up my XZL tires. Snuffy is now about $5000 into a 4BT/3053A swap on his M715 the last time we talked a few months ago.

His crazy expensive 4BT swap is what I kept thinking of as I was writting replies to this thread.

 

[spicergear]

Ha! You sucker! Yeah...the pics I took years ago! LOL!

That also reminds me of what else M715 guys can do. Tim, you know this but for some others...that's an NP205 with the NP200's factory e-brake on it. The rear output housing uses different bearing between the two cases but with just a little machining to the brake bracket, you can turn the step into it so it will be relieved to allow room for the 205's different bearing. I spun it on a small lathe.

 

[67_C-30]

I helped a friend put a 4BT in a CJ-7 a few years back, and though we both it was an awesome idea at the time, he hates it now that its in the Jeep. The 4BT vibrates terribly and does not run smooth like a 6BT or other V8 diesels. He did extensive research trying to find the "problem". He changed injectors, changed style of engine and transmission mounts, took it to a diesel mechanic and had it timed up, and still it vibrates. There's tons of other threads about this on the net. Some people don't seem to mind it, but my advice would be to try to find someone has a 4BT in something similiar, and see if you mind it. His Jeep, like your M715 has no carpet, no underhood insulation, and a soft top. It drones and shakes worse at different RPM ranges, and at times it makes the hood resonate like it has a big electric motor mounted to the bottom of it. My buddy says "it shakes like a Shovelhead with loose rod bolts" -lol

 

[bcowanwheels]

ITS the nature of a 4 b engine. there industrial engines that seen automotive uses. i have 15+ 4bt's and i dont want one in any of my m715,s. some folk swear by them but the only advantage is better fuel milage but you sure pay for them mpg,s. so wheres the advantage. also the fuel system is extreamly sensitive in diesels and it will pay dividends if you put the best fuel filter setup you can find on them (raycor ). JMO
BOB

 

[Tanner]

Mine ran and worked very well in the M715 with the NV4500's decent OD and even with the stock deep axle gearing. One thing...this set up is tough to round up if you don't have donor parts and have to find them individually. A 6.2 manual flywheel isn't the easiest thing to find. The drive is VERY mechanical feeling. When you're in the pedal you move forward and with the deep axle gearing you move forward NOW. Same with decelerating...you lift and it slows fast. I never had it loaded but it did seem to work well while I had it.

Don't know where you are looking, but 6.X manual trans flywheels are extremely easy to find...

Advance Auto Parts: New Flywheel by Perfection Clutch - Part 50-2710

$167.99 - (matches GM Casting# 14050525)

'Tanner'

 

[Tanner]

THIS IS A JOKE......" Mounting a 4Bt is easy ". HOW ABOUT ALL THE PLUMBING & COOLING , EXHAUST, CLUTCH LINKAGE, DIFF CLEARENCE, FUEL SYSTEM, AIR FILTER ASSY., BATTERY, THROTTLE LINKAGE, ELECTRIC WIPERS ON AND ON IT GOES........ AND BY THE WAY A 6.2 IS A JUNK ENGINE. ITS WHY THEY WENT TO 6.5. DO YOURSELF A FAVOR AND PUT A SBC IN THERE IN A WEEKEND AND BE DONE WITH IT IMO AND I,VE DONE THEM ALL.

The weaknesses of the 6.X block are well known, and well noted. That being said, the 6.2 block was a much better block than the 6.5, UNTIL the new & improved 6.5 blocks came out in the past half-dozen or so years. The 6.2 is not a junk engine when maintained & used as it was intended; it was designed as a light-duty diesel for fuel economy, not for yanking houses off their foundations... there have been numerous users of 6.2's that have gotten 200k+ out of them, and there have been users seeing less mileage/longevity forom them... YMMV.

The move to a 6.5 in military applications was due to GM phasing out the 6.2 & moving to the 6.5 in civvy trucks.

'Tanner'

 

[spicergear]

Yeah, but that's the cost of a good clutch set up...when you should be able to find one junk yard for $50 and not have well over three bills right there. Now you see... HA!

 

[bcowanwheels]

Any engine block that breaks in the main bearing area is junk imo

 

[spicergear]

Tough to argue with that-