6.2 Civi Vs. Military

[Lawrence of Arabia]

Can anyone tell me the difference between the Civi & Military 6.2? I have a used good, low mileage, Civi motor I am sitting on as a spare. I would not want to use it in my Military trucks if I would be losing anything by using it Vs. replacing it with the correct engine or rebuilding the one in the truck.

 

[jimmy-90]

What year truck did it come out of and does it have a serpentine belt. If it is a J-code 6.2L civi motor with a serpentine belt then as far as civi vs military goes the serp belt 6.2 is supposed to be a better motor than the civi or military non serp belt motor. If it is a three belt civi motor you won't be losing anything vs the military motor as long as this civi motor is a J-code motor. I think the only difference in the military 6.2 is that the injection pump is flex-fueled.

 

[brianrbull]

What does "Flex-Fueled" Mean?

 

[Nick Danger]

If it's a 1982 civi it's down about 10 ,15hp or so

 

[raiburn]

I saw specs somwhere that a civy 6.2 is rated 130HP, and 230 FPT.
A Mil. 6.2 is emissions free, and rated 155 HP, and 255 FPT.
Joe.

 

[48cj2a]

I just bought a 87 3/4 Crew Cab for its engine and it was a J code. The only difference was gauge sending units, and CDR valve was behind the RH Alt rather then under the air cleaner.

I've heard the same about the IP. Military uses all kinds of fuel grades and quality depending upon the supply so the IPs are setup special for it.

 

[Johnn Bravo]

I lost the bottom end of the motor in my first M1009, replaced it with a 6.2l from my 1982 suburban, think it was a C-code. As for power I know the J-code should make more, the civi engine I put in runs like a gas engine, makes much less noise then the military engine, and I don't think I lost anything compared to the military engine. I am more pleased with having the civi one in there just for the lack noise alone.

One thing you might want to consider is the oil cooler lines. If I recall correctly the fittings on the engine didn't match up to the cooler lines. I was able to piece it together with parts that I had left over, but I'm sure if you live in a larger city you could get lines made with the right fittings on.

 

[rnd-motorsports]

Alot of guys will disagree. But My dad is retired from detriot diesel and a hilo driver for the assmbly line of the 6.2 and a best freind worked development He says the dif between the c code and J code is the EGR and that the injection pump is turned down a bit and a small timing setting dif on the c code witch means about 15 hp less on the c code . he also says that the only dif in the cucv and the civi J code is the cucv used a dif glow plug. for military spec. the serpentine belt was not done to the cucv to keep all military trucks the same becouse of the daul alts no dif in power! that being said he says the newer the engine cucv or civi the better as they did updates as the years wen't to correct problems and short falls. Others will say dif.

HAPPY THANKSGIVING!!!!

 

[ken]

I have swapped these around for years. The difference between a C code and a J code is the EGR. The J doesen't have one. If you have a 6.2 with a serp belt you can easily swap all the Mil parts onto it. And you will have to swapp the water pump out. They turn different directions. It will also have the desirible single plane intake manafold. As far as the HP ratings go. The C motor is less. The intake manafold is very restrictive. Remove the EGR from the exaust manafold and install the J intake and presto. You now have a J code engine. HP is also controlled by the fuel rate setting. Again easilly adjusted. The IPs were upgraded as the years went by. Plastic internal parts were replaced with metal. Greatly improving the life span.

 

[Recovry4x4]

The IP parts were hardened in the Mil pumps. Also for you guys stumbling into 1982 engines, they came from the factory with coarse thread injectors. Another consideration is the engines from the G series of vehicles have shorter injectors.

 

[mf5129]

emission differences and pump calibration.you can reinstall orginial accessories.the j code is better because its simpler.easier to obtain parts for.

 

[Lawrence of Arabia]

WOW. Thanks guys for all your input. Good info. from all.

 

[dragonwagon]

Alot of guys will disagree. But My dad is retired from detriot diesel and a hilo driver for the assmbly line of the 6.2 and a best freind worked development He says the dif between the c code and J code is the EGR and that the injection pump is turned down a bit and a small timing setting dif on the c code witch means about 15 hp less on the c code . he also says that the only dif in the cucv and the civi J code is the cucv used a dif glow plug. for military spec. the serpentine belt was not done to the cucv to keep all military trucks the same becouse of the daul alts no dif in power! that being said he says the newer the engine cucv or civi the better as they did updates as the years wen't to correct problems and short falls. Others will say dif.

HAPPY THANKSGIVING!!!!

This is good advice on most all motors iv found , the Ford 7.3 was the same way , the last year they built it was the best year to have for just the reasons you mention . Now with the over the top emissions 07 and never , not so much the case .

 

[Lawrence of Arabia]

So where do I find the "J" "C" "G" Code? Is it in the VIN? All I have is an engine. Is it in the stamping on the block?

 

[Lawrence of Arabia]

Anyone?

 

[patracy]

I want to say it's the 8th digit.

Also note, civi 6.2's and 6.5's in the 1/2ton lines had nasty EGR setups. A common upgrade was to ditch it in favor of a J code intake.

I wouldn't play too much with timing on a 6.2/5 due to the high compression ratio, you'll end up breaking something quick if you turn it up too much.

 

[Recovry4x4]

Yes, 8th digit on the VIN. Usually a sticker is on the engine somewhere as well. The only 6.2 engine codes are C and J. G was a series of vehicles, the vans. My burb has a "C" engine in it and in the intake is a large tumorous growth called the EGR. I have a J intake ready for when I upgrade injection pumps.

 

[southdave]

Rear driver side block ,between the hesd and the block to fine the Engine number

 

[gschooley@gmail.com]

1984 gmc m1008

Can anyone tell me the difference between the Civi & Military 6.2? I have a used good, low mileage, Civi motor I am sitting on as a spare. I would not want to use it in my Military trucks if I would be losing anything by using it Vs. replacing it with the correct engine or rebuilding the one in the truck.

My kid has a 1984 GMC with a 6.2L Hummer, it had a GMC intake manifold
with a whole bunch of EGR junk connected to it. We got a military intake which
is wide open without the EGR crap, which we are about to swap out. But I don't
know what to do with the wiring to keep the computer happy.

 

[patracy]

My kid has a 1984 GMC with a 6.2L Hummer, it had a GMC intake manifold
with a whole bunch of EGR junk connected to it. We got a military intake which
is wide open without the EGR crap, which we are about to swap out. But I don't
know what to do with the wiring to keep the computer happy.

There shouldn't be any "computer" to it. It's all mechanical.