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MaxPF's 6.2 build

MaxPF

MaxPF

1/2 ton status
Joined
Apr 13, 2006
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Chandler, Arizona
OK, so I scored a 6.2 J-code motor out of a 91 one ton crew cab (In my garage poll a 383 stroker won over the 6.2 with a turbo 29-5. I must be out of my mind :doah:). The engine will be complete, including the accessories, the goofy filter on the firewall (is there something better available?) and the hydroboost. Is there anything else needed from the donor to swap it into a gas truck?

It has 227k on it, so I plan on rebuilding it (possibly with splayed caps, otherwise definitely with a main cap truss). If Colby or someone else who has rebuilt theirs can be so kind as to tell me what you used for pistons I would appreciate it :bow: Did you punch it over or sleeve it? What other parts did you use? Any other gotchas with a 6.2 rebuild? I haven't worked on one since the late 80's when I did my Army stint and wrenched on HMMWV's and CUCV's, so any tips would be appreciated :deal:
 
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That reminds me , I have 3 rather large pdf files for repairing and rebuilding CUCV's . Don't remember where I got them , but I have them :thumb:
 
If I recall the good way to build a 6.2 is with the ceramic coated 18:1 pistons, stud girdle, Gear drive, 4911 pump and 6.5 TD injectors...but it's like any build. Your budget will determine the parts you use more than anything else.

Rene
 
tRustyK5 said:
If I recall the good way to build a 6.2 is with the ceramic coated 18:1 pistons, stud girdle, Gear drive, 4911 pump and 6.5 TD injectors...but it's like any build. Your budget will determine the parts you use more than anything else.

Rene
Click to expand...

Any idea on the cost of the build they way you just said?
I already have a hummer 6.2 block and crank, and want build an engine slow, I have no ruck to put it in yet so it will be as money comes after I DO get a job :o
I also have the Turbo BANKS so it will be turboed and i think the 18:1 would be the good choice.
:D
 
I agree with imiceman:D

BTW, I also have an Fuel Injection Pump model DB2831 4911, the suggested upgrade, PM me if you are interested.
 
OK so here's the filthy bastard:




Here's the information sticker on the side of the air cleaner. It's an RPO LMM motor advertised as making 165 horsepower:



Here's the bare block. It definitely needed a bath, and it along with the heads and crank are at the machine shop right now:



Main caps and pistons. The 3 center main caps will go bye-bye, and 3 billet steel caps with splayed outers will take their place:



Fortunately the main webs appear to be crack-free. I will know for sure after the block is magged. The heads likewise appear crack free, although they aren't as easy to tell visually until they are cleaned. Once again, magnafluxing will find any problems:



Here's the remaining pile of parts:



The cam is junk - a piece of debris made it's way into the #3 journal and badly scored it. Some of it got into the crank as well and scored the #3 main and a rod journal. The crank could be ground undersize, but this isn't reccomended with the rolled fillet, nitrided 6.2 crank. I will get a replacement from Peninsular instead. The engine was running when I got it, but it had a miss. When I pulled off the left side valve cover I found out why.. The intake pushrod on #7 was missing, and the retainer had come out of the lifter. I found the pushrod later when I pulled the oil pan. Can anyone tell me which one of these doesn't match the rest:



There was barely a mark on teh crank where it grabbed the pushrod, wadded it up, and spit it into the pan. Unfortunately some of the chewed up metal from the pushrod is probably what got into the oiling system, through the filter bypass, and wiped out the journals on the cam and crank :doah:. Fortunately, besides that and the oil pump (probably - I am replacing it anyway) no other damage was done.

I got everything with the engine, including the rectangular fuel filter assembly, all accessory brackets/accessories, the hydroboost, etc. It is a J code motor, so there is no EGR either. I can't wait to get it back from the machine shop and get this show on the road. :saweet:
 
Cool, I really like the custom pushrod. :D

I'd lose the rectangular fuel filter and go with a spin on and a Racor with water seperator.

Rene
 
tRustyK5 said:
Cool, I really like the custom pushrod. :D

I'd lose the rectangular fuel filter and go with a spin on and a Racor with water seperator.

Rene
Click to expand...

Got a link to a pic of the filter you're talking about?
 
Here is a link

http://www.usdieselparts.com/racor.cfm

I'm pretty sure the one I have is the 200 series. I also have the earlier GM spin on. The spin on is 10 micron, the Racor is 2 micron plus the water seperator on the bottom of it. I'll have to dig for pic's of the set-up on my Jimmy.

Basically the problem with the Model 80 square filter is that it commonly leaks on the backside of the housing. Not usually enough to see any fuel dripping, but more than enough to allow air to find it's way into the fuel line (and cause an air lock)

Racor also makes fuel filters with heater elements too.

Rene
 
Those look like nice units! Thaks for the link :waytogo:

EDIT: Another question: do you use a singe 2 micron filter, or do you have 2 filters, say a 30 and a 2 micron, in series?
 
hey. i'm glad you went diesel - you'll be happy w/ it for a wheeler when you're done. the low end torque will really get you stoked.

one note: all the research i've done says DO NOT allow the machine shop to turn your crankshaft. if it needs turning, you need a new crank. i went w/ larger pistons - just standard ones from my favorite auto parts store. i didn't do any of the mods tRusty mentioned, tho i would have liked to. it just ended up being too pricey. it's a pretty straightforward build. don't mess up the timing - it's an interferance engine. :)

that pushrod is out of control!
 
I run two in series. One much finer than the other. My theory is the first one catches the bigger bits, then the second gets whatever is left and the IP/injectors are happy. I'd guess I get two to three years out of a pair of filter canisters.

my first filter is 10 micron (I think) and the Racor filter is 2 micron (for sure)

Rene
 
colbystephens said:
hey. i'm glad you went diesel - you'll be happy w/ it for a wheeler when you're done. the low end torque will really get you stoked.

one note: all the research i've done says DO NOT allow the machine shop to turn your crankshaft. if it needs turning, you need a new crank. i went w/ larger pistons - just standard ones from my favorite auto parts store. i didn't do any of the mods tRusty mentioned, tho i would have liked to. it just ended up being too pricey. it's a pretty straightforward build. don't mess up the timing - it's an interferance engine. :)

that pushrod is out of control!
Click to expand...

neither of my 6.2's have any of those mods either. Both of mine have never been rebuilt. When either one needs a rebuild I'll probably do some of that stuff. Specifically the stud girdle, gear drive timing. The ceramic coated 18:1 pistons are really only a benefit if you're planning for a turbo. I'm still undecided whether I want to run a turbo. I have an ATS kit here...but which truck to put it on? :D

Rene
 
Well, the current build plans are for splayed intermediate caps and stock compression pistons. While I will turbo the motor, I don't plan on more than about 7psi, so stock compression pistons with hard anodized crowns should be fine. The emphasis is on decent power and reliability, not a 300+HP 6.2. Also, 18:1 pistons tend to cause hard starting in cold weather. I don't want to be up north in the winter trying to start a cantankerous, cold-blooded diesel :doah:
 
I think all IDI diesels are harder to start when cold. I hadn't heard that 18:1 pistons made cold starting noticeably harder though. You'd think it'd crank over a bit faster which would make up for the lower CR a bit.

I did read somewhere that the ideal diesel CR is actually between 13:1 and 14:1 which surprised me.

Rene
 
boy, the CR you listed as ideal is surprising! do you recall where you learned that?
 
Can't remember now, although I think it may have been an employer of mine that was a heavy duty mech at one time.

Rene
 
tRustyK5 said:
neither of my 6.2's have any of those mods either. Both of mine have never been rebuilt. When either one needs a rebuild I'll probably do some of that stuff. Specifically the stud girdle, gear drive timing. The ceramic coated 18:1 pistons are really only a benefit if you're planning for a turbo. I'm still undecided whether I want to run a turbo. I have an ATS kit here...but which truck to put it on? :D

Rene
Click to expand...

On the c2500
You want your turbo on the DD that sees Highway miles often.
The off road truck will not use it as much as a DD.
By the way this is what I had on my perkins, I guess now I know it's a racor turbine style after I Parted the truck. :o

DSC00174.JPG

DSC00175.JPG
 
I think turboing the 83 C1500 will eat the 700R-4 for lunch...and I really want the truck to remain stock. It's more of a commuter than anything else, and as a NA 6.2 it'll do better on fuel.

The Jimmy has the NV4500 and is more of a 'fun' truck so if I turbo either it'll likely be the Jimmy.

Rene
 
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