6.5 with 6.2 heads

[D rat]

Im looking at a 6.5 marine engine with 6.2 heads, we have had the pan off and if this engine isn't new then it's a fresh rebuild, we did start it in the crate and it burbled rite up.

what I dont know is what advantage will it be having 6.2 heads on a 6.5 block. Any help will be appreciated, thanks Chuck.

 

[tanman_2006]

Not really any advantage. You might have an issue putting turbo manifolds on due to injector angle.

 

[D rat]

I have found that this was a military engine for a humvee and that the heads are third generation heads, it was then converted to a marine engine and still has all the 24 volt accessories.

 

[tanman_2006]

Are you sure its a 6.5 bottom end?

What do you mean by 3rd gen?

 

[WarWagon]

6.2 NA heads? Check the precup size - although it only matters when going with a big turbo and lots of fuel. Unless you are doing a big turbo then it doesn't matter. The 6.5 injectors on 6.2 heads are tight to the turbo manifold. The 6.2 NA precups smoke more than 6.5 turbo precups, but, with factory turbo's you won't notice. I have run every combo, but, 6.2 heads on a 6.5. They bolt up and will work. The only exception is 1982 red block heads with fin thread injectors and van engines. Vans have completely different intake port angles. HUMMER engines can have oil pan clearance issues in our trucks.

Any cracks in the main bearing webs when the pan was off?

You should put in new rings and deglaze the cylinders now while the engine is out.

 

[D rat]

Are you sure its a 6.5 bottom end?

What do you mean by 3rd gen?

Yes I will be going back on moday to get some numbers off the head and block.

I was told 3rd generation, I believe that it was the last year of the 6.2.

 

[D rat]

6.2 NA heads? Check the precup size - although it only matters when going with a big turbo and lots of fuel. Unless you are doing a big turbo then it doesn't matter. The 6.5 injectors on 6.2 heads are tight to the turbo manifold. The 6.2 NA precups smoke more than 6.5 turbo precups, but, with factory turbo's you won't notice. I have run every combo, but, 6.2 heads on a 6.5. They bolt up and will work. The only exception is 1982 red block heads with fin thread injectors and van engines. Vans have completely different intake port angles. HUMMER engines can have oil pan clearance issues in our trucks.

Any cracks in the main bearing webs when the pan was off?

You should put in new rings and deglaze the cylinders now while the engine is out.

As far as turbo, I have a complete gale banks turbo system and an ATS turbo system.

The oil pan is a marine version buti have a 6.5 truck pan.

we plan on pulling the heads and installing studs, didn't think about rings.

No cracks, I have three 6.2s and only one is crack free.

 

[Chevypoor]

Both 6.2s I have had (both 93s in gmt400 trucks) were identical to the 6.5 except for the crank and pistons, they even had one piece seals. That included the heads. Last year in the trucks was 93, not sure if the military had them made new for them after 93 other than reman motors, also not sure the 6.2 was available as a reman after 93 and if so for how long. In either case I would imagine since it a late run/ last year set of 6.2 heads then everything should be identical to the 6.5 heads including the injector angle. Ts heads are from a 93 6.2 and they fit with zero issues on its 93 6.5 block. I did change the precups over to the newer diamond pre cups.

 

[Burning oil]

IIRC 93 6.2 is a 599 casting on block.

 

[D rat]

I got some # and some pics today.

The block is 12555506 a 506

The heads are 10137567

the sticker says that is a GEP build and AM General didn't stat production till 2000 so that means the date code is not the same as the pre date codes and I cant tell what the date code reads so I hope someone here has an idea.

Thanks

 

[ak diesel driver]

try this http://www.thetruckstop.us/forum/threads/late-6-5-date-codes.28056/

 

[Burning oil]

The 506 from GEP/AMG is about as good as it gets in the 6.5 world. P400 is next step up. Its possible you have a P400. Does it have the main stud girdle on it with a cast alluminium pan?

 

[WarWagon]

They got anymore of those for sale? Nevermind on cracks as this version isn't as prone to them... I would still re-ring it and consider head studs while you are at it - recall the head bolts are TTY and not reuseable. Freash re-build, but used, I have not had luck with rings that have seated properly and minor cyl rust from sitting. This is why I recommend a ring set.

 

[D rat]

The 506 from GEP/AMG is about as good as it gets in the 6.5 world. P400 is next step up. Its possible you have a P400. Does it have the main stud girdle on it with a cast alluminium pan?

It has the cast marine pan and my buddy can't recall if it has girdle, any idea what the year is ? I can't make the year in the picture.

Thank you all for your response.

 

[D rat]

They got anymore of those for sale? Nevermind on cracks as this version isn't as prone to them... I would still re-ring it and consider head studs while you are at it - recall the head bolts are TTY and not reuseable. Freash re-build, but used, I have not had luck with rings that have seated properly and minor cyl rust from sitting. This is why I recommend a ring set.

This is the only one and I am getting the headstuds and as far as rust, this is Yuma Az, we don't have rust so I'm hoping that they are clean. Once I get it home my neighbor is a catipilar mechanic.

 

[ak diesel driver]

can't make out the letter

 

[Will L.]

Can you take a picture of the side of the block where the oil pan bolts on? We should be able to tell if you have a home run or a grand slam.

 

[WarWagon]

Marine engine = rust if the cylinders weren't oiled before unknown storage time. It's likely minor, but, adds to the blowby.

 

[Burning oil]

It has the cast marine pan and my buddy can't recall if it has girdle, any idea what the year is ? I can't make the year in the picture.

Thank you all for your response.

Guessing Jan 4th ????
A picture of oil pan flange would be good.

 

[great white]

Date code format for GEP blocks is

00 00 X

That looks like

10 04 (missing letter)

That would be 10th month, 4th day. Oct 4, year undetermined.

However, the numbers and location look a little wrong. Maybe its just the marine hardware throwing me off.

Is that the pad on the block immediately behind the rh side head?

Like so:

In addition to the give away lower block skirting/girdle, the p400 has another dead give away feature: