6.2 HMMWV in my GMC

[Gunfreak25]

I am putting this new HMMWV motor into my GMC soon. I am using the Th400 that is already fitted to the truck and has been used in the truck. The transmission is setup for a rubber mount. For the motor, I really want to make some solid mounts. They are so easy, and I could be done in under a couple hours. Problem is, the opinions on this setup are as varied as ever. Some say it will be fine since the rubber trans mount will provide some flex in the system. Some day the rubber/solid combo will crack the bellhousing. Some say, yada yada.

What do you guys think? It will be be an asphalt queen, light duty grocery getter. Not like i'll be drag racing or anything. I figure vibrations are a non issue, seeing as how the truck weighs over 13,000.

 

[G-Force]

Don't do it......you'll eventually break something.......probably alot sooner than you think

 

[jwaller]

holy cow thats going to be one slow truck.

 

[Stan Leschert]

holy cow thats going to be one slow truck.

It would be hard to get much slower than it was ... or is right now!

Get that thing moving!

 

[Boss Doug]

Go with rubber mounts!! It's not much harder to make than solid mounts.

 

[big block 88]

Solid motor mounts on a diesel is never a good idea unless it is a dedicated drag truck or sled puller. And that being a 6.2 it will be neither of those things.

The harmonics and vibration will shake and rattle that old Jimmy to death and will lead to some cracking or breakage of somthing down the line.

I like your idea here with the 6.2. Some people think the 6.2/6.5 detroits are junk and weak, I can tell you they are not with the right amount of work and TLC they can be very powerful and reliable. It will never be a Cummins 12V or a modern common rail diesel but they are good little motors. The missconception on the 6.2/6.5 detroits being junk is based off of hearsay and rumors. They put these motors in large delivery trucks and they were worked well past what they were intended for and they had issues. So don't buy into the fellers who say "I know a guy whos cousins unkle's brother's sister's friend's niece's neighbor had a 6.5 that broke a crank shaft and they are all junk.

Best of luck sir.

 

[kweb434]

Go with the rubber mounts.

 

[bubba_got_you]

id use a 700r4 trans, lower first and 2nd gear and an o/d i would also ad a turbo for that extra "UMPH"

 

[91W350]

The difference in fueling rates on the 6.2 engines is tremendous. I have a really nice M1008, but it is a pokey puppy. It never bothered me as I am usually empty or only haul what fits in the bed on recoveries. When my starter bolt broke, my son brought my M1009 over to pull me home. My M1008 accelerated faster behind the M1009 than it can on its own. Maybe it is time to learn more about the pumps. My other M1009 ran good, but it was not nearly as strong as this one is. My previous M1008 was a much stronger running truck as well. I guess what I am working up to is that before I went turbo charged, I would have somebody in the know set up the pump.

Power wise, I think you will be right on the money, it is not like you want a rocket ship anyway. The 6.2 should work nice and smooth in there and I love the rhythmic rattle of the 6.2. I do agree it would be best to use a rubber or polyurethane engine mount. I would look at the engine mounts a lot of guys are using on their big block street rods. They are simple single pivot bolt mounts with a polyurethane bushing. Very strong, very easy to assemble, tear down and do not cost much to build. Glen

 

[superburban]

I love this idea. Use rubber mounts for sure!

Keep us updated as you progress.

 

[Gunfreak25]

Wow! Thanks for the replies. I will definitely go rubber then. It won't be a super fast truck. It was never designed to be. The 6.2 will produce the same amount of power as the original 302, with a little more HP while delivering better fuel economy. Besides, the joy in owning these is to slow down enough to see things you'd otherwise miss in another vehicle. For an around town vehicle, it will do the job very nicely. Thanks again for all the quick replies, everybody here deserves a grammy for putting up with my non stop questions.

 

[cjtroutt]

I am putting this new HMMWV motor into my GMC soon. I am using the Th400 that is already fitted to the truck and has been used in the truck. The transmission is setup for a rubber mount. For the motor, I really want to make some solid mounts. They are so easy, and I could be done in under a couple hours. Problem is, the opinions on this setup are as varied as ever. Some say it will be fine since the rubber trans mount will provide some flex in the system. Some day the rubber/solid combo will crack the bellhousing. Some say, yada yada.

What do you guys think? It will be be an asphalt queen, light duty grocery getter. Not like i'll be drag racing or anything. I figure vibrations are a non issue, seeing as how the truck weighs over 13,000.

Nice to see 6.2L will be used for that app.
As for engine and trans mounts do rubber dont do solid the Th400 will end up with brakeing the trans bell case I done two of them years back and also try to use the tork bars and cover to help the releave the stress on trans case.

 

[Gunfreak25]

Yeah, they worked well for the HMMWV and my 6.17 gears should take a lot of load off the transmission and engine, so as not to overwork them for this large application. I will be installing an oil cooler like the HMMWV as well as running the biggest trans cooler I can find.
I am going to make the mounts out of flat plate, they will look just like the mounts used on the military motor crates.

http://www.olive-drab.com/images/mvg_demil_375.jpg

They will be secured with 2 bolts each to the frame (removable) and cushioned with the old style rubber biscuit pads. Will 3/16" plate be sufficient for this?