M135 Engine swap, Vortec chevy???

[6x6XL]

Hello all. i am in a big debate on what to do with my truck right now. i would like to swap the GMC inline 6 out for one of the 350 Chevy Vortecs (fuel injected) i have in the shop. This of course drives a transmission change and the biggest issue will the transfer case. I was thinking of running a regular chevy t-case and building some sort of chain drive unit to drive the aft most axle off the a single driveline to the rear. from the mid axle yoke to the pillow block. The truck is a 1951 M135 that is rust free (except the bed) and in great shape. my debate is: will this work? Is it worth the work? I dont want to destroy a classic piece of military heritage, but if i keep the truck and dont sell it, i would like it to be more road and fuel friendly. i have a few months to decide as im out of the country for work for a few months. Thanks for any advice.

 

[dmetalmiki]

It is your truck, so any modification you do to improve it for funtionality and your pleasure is a worthy cause. That is a project that will definately give you great staisfaction once you have acclompished it. Anyone oberving the finished result would be nothing but impressed.

 

[Section8]

Keep the transfer case. It is independant from the tranny. Biggest problem will be your drive shaft between tranny to transfer case. That's as easy as having a shop make you one to the length you need with stock yoke and what ever corresponding yoke you need to mate to your tranny.
Biggest most important thing to remember is the front axle is COUNTER ROTATIONAL and the transfer case is set up for this.
If you use another transfer case you will have to find one set up with the front drive counter rotational and passenger side drive. Hard to come by as far as I know.
Easier to just keep the stock tranny for your needs of an engineer tranny swap.
I plan on doing the same with a 6BT in mine.

 

[amgeneral72]

Had a friend that put a 455 Pontiac engine in a M211 somehow. He thought it would make it go faster. Ha Ha. He was sorely disappointed

 

[Heath_h49008]

Hmmm... but it does sound like a good idea for an M715.

 

[6x6XL]

i wasnt aware of the counter rotational front drive. That is good info. i think adapting the tranny to a 350 would be challenging espescially with big bump in power. I know the tranny is tough, but i think if i do the swap i would probably use a GM T-case and a divorce shaft between the stock t-case to still have ability to use a low range. Im not looking to go real fast, but im a believer in modern fuel injection lol. Kinda makes me wonder how much torquing /power/ binding the stock t-case can handle.

 

[6x6XL]

Hmmm... but it does sound like a good idea for an M715.

If i had my hands on a m715 i would 6bt all day. those trucks are sweet and to add that diesel in...awesome!

 

[amgeneral72]

M715's are really cool trucks. I always thought the were just a little over sprung. They will beat you to death off & on road.

 

[topo]

The M211 /M135 transfer case dose not have a low range .It's single speed 1.16 to 1 .

 

[m1010plowboy]

What is the truck going to do?

If it's an asphalt queen and you're not playing in anything slick, leave out the front drive-shaft. I pull the front shaft to run around the city, practice drifting in the winter and do parades. I put it back in to pull Seano11 out of the mud every couple of months so it is handy, but not required. You could run the 350 to the rears and be done. IF we get this right you should be able to spin the rears off the line, slightly lifting the front end if she hooks up and hit 32 seconds in the 1/4 mile if it doesn't break...or brake. Gear ratios, max rpm, gearing, over-drive, shift timing, torque and breaking point should all get reviewed on paper first.

With any engine you'll have brake system challenges however an upgrade to a modern 'dual circuit' brake system should be considered if you're doubling your horse power. An option is to bolt the compressor onto your engine choice and change pulleys to run it in the serpentine belt. Pros and cons on both methods so I will anxiously be waiting for which sample of yours I'll be following.

Engine conversion links on post #69 gigity on this thread http://www.steelsoldiers.com/showthread.php?100212-My-M135-Quad-cab

 

[rosco]

You can modify the T-case to be Hi & Low range, by changing the big idler gear in there, to not rotate/idle (by removing the bearing, but that complicates the use of the winch, because there will be no neutral. If you do that, then you have to manually shift the T-case to forward, or reverse, when you change directions - it has a mechanical sprague clutch for that, and the direction change is done, now automatically by the rear of the tranny. To simplify all this, just use the earlier version of the T-case, but it won't handle as much torque (its a bolt up). I kept the 302, but put the 40's Clark 5 speed behind it, using an old GM bell housing. THEN there is the clutch peddle & linkage. In short, the GM 211/135 does not support modification, beyond what it is. At the time though, I was young & none of the above registered, as a result, I no doubt drove them some 50K, over the North country. And yes, running when parked!

 

[6x6XL]

Rosco- Thats tractor is pretty sweet, ive never seen one.

If i run the 350/4L60e combo i have in the shop, i think ill figure out a way to mate the stock t-case to somthing like a dana 300 t-case (clock-able) and just not use the front output. IDK im going back and forth. this is my first duece and i think i should have got an m35, but i didnt know better lol silly me.
I havent seen a lot of mods to these trucks. if i build it, it will be for a lot of off roading. i have a half way done crew cab for it too that would go on with a shorted bed.
As far as the the compressor goes i should be able to adapt it to the eninge. we convert and use a/c compressors for air all the time on the jeeps we've built, so air shouldnt be too bad.

The biggest thing i go back and forth on is the actual build. the truck is the one in my avatar and its a nice truck for a 51. ive seen a few others and mother nature hasnt been too kind. i kinda think if someone wanted a restro truck this would be the one, so i would feel guilty about cutting it up.

 

[Jeepsinker]

That truck is pretty clean to start cutting on it... I don't think I could do it.

 

[rosco]

If you start doing those changes, the work will be endless, and it will be very expensive. Nothing is easy or straight forward on the GMC -- I know very well. You will be money ahead, if you just park or sell it, and get a multifuel. Parts are cheap, lots known about them, and far easier to get on the road. Its a BIG job you have outlined, and if you don't finish it, it will just be a chopped up scrap. Good Luck

 

[6x6XL]

That truck is pretty clean to start cutting on it... I don't think I could do it.

Yeah that's kinda how I feel, but ive had it up for sale for a while and didn't really have any takers which I thought a odd, its got a clean title and is in good shape, I didn't think the market for these trucks was that narrow. I had to take it off the market because I had to leave the country for work (military) and will be hard to do a sell until I back this summer.

 

[6x6XL]

If you start doing those changes, the work will be endless, and it will be very expensive. Nothing is easy or straight forward on the GMC -- I know very well. You will be money ahead, if you just park or sell it, and get a multifuel. Parts are cheap, lots known about them, and far easier to get on the road. Its a BIG job you have outlined, and if you don't finish it, it will just be a chopped up scrap. Good Luck

That's kinda my school of thought too. I kinda want to put my time and money into this 76' Dodge dart that I ive been trying to get my hands on before I even got this truck. I took delivery on the Dart a month before I left, so now im kinda stuck between the two lol.