6.2 heads on a 6.5

[Cannoncocker]

A friend is running a non-turbo 6.5 in his M1009 and blew a head gasket. Pulled both heads and found one head to be cracked in several places. His question is can a set of heads from a 6.2 be used on a 6.5? Thanks, John

 

[tamecrow]

A friend is running a non-turbo 6.5 in his M1009 and blew a head gasket. Pulled both heads and found one head to be cracked in several places. His question is can a set of heads from a 6.2 be used on a 6.5? Thanks, John

The 6.2 heads will fit the 6.5 but the injector angles may be different. You may have to manipulate the lines a bit but they will fit.

 

[67_C-30]

Yep, what tamecrow said. I've done it several times.

 

[Patattack]

Very common problem with the 6.5s And also the 6.2s. It because the water jacket on the heads are to far away from the cylinder. If you find heads from a 1997 and later GM fixed that issue by making the jackets in the head bigger. But if your short on time and money then go with that.

 

[jdknech]

i used 6.2 heads on a 6.5, the injector angles ARE differant, and a PITA to get the lines re-bent correctly, also to keep the compression ratio correct, you will need 0.010 oversized head gaskets.. the correct C/R is 21.5-1 on the 6.5

 

[tamecrow]

i used 6.2 heads on a 6.5, the injector angles ARE differant, and a PITA to get the lines re-bent correctly, also to keep the compression ratio correct, you will need 0.010 oversized head gaskets.. the correct C/R is 21.5-1 on the 6.5

All depends what year the 6.2 heads are. On the later 6.2 heads the injector angles are identical to the 6.5. I just put a set of '91 6.2 heads on a '97 6.5. No modifications were necessary because the injector angles were identical. That's why I said you "may" have to readjust the lines to fit. Even on the older style heads you won't have too much difficulty reshaping the lines using a good tubing bender. I'd use 6.5 head gaskets even though you shouldn't have any trouble using the 6.2 gaskets on a naturally aspirated 6.5 engine.

 

[Cannoncocker]

Thanks to all for the great info. We have a late 6.2 (year unknown) that was removed from a Hummer. We will pull the heads next week and have them checked out at the machine shop. If they come back good and armed with the information supplied by everyone we will have him up and running again. Thanks again, John

 

[jdknech]

the heads i used were off of a hummer "J code" engine.. more then likely the same engine your using, the compression ratio shouldnt be to big of a issue because of the 6.5 being a non-turbo... i was very careful to keep the C/R correct on mine becacause I'm pushing 15-18psi of boost.. didnt want to blow the heads off (again )

 

[Cannoncocker]

Good info. The hummer engine we are using is a J code. It was not a running motor when we got it but it was complete with clean oil and fresh antifreeze. Like a box of Cracker Jacks you don't know until you open it up. If the heads come back from the shop with a clean bill of health and the weathers good (showed today) I want to turn some wrenches. We are going with top of the line 6.5 head gaskets. Thanks again, John....

 

[67_C-30]

Good info. The hummer engine we are using is a J code. It was not a running motor when we got it but it was complete with clean oil and fresh antifreeze. Like a box of Cracker Jacks you don't know until you open it up. If the heads come back from the shop with a clean bill of health and the weathers good (showed today) I want to turn some wrenches. We are going with top of the line 6.5 head gaskets. Thanks again, John....

I'd highly recommend going with new head bolts, if you haven't bought them already.

 

[patracy]

the heads i used were off of a hummer "J code" engine.. more then likely the same engine your using, the compression ratio shouldnt be to big of a issue because of the 6.5 being a non-turbo... i was very careful to keep the C/R correct on mine becacause I'm pushing 15-18psi of boost.. didnt want to blow the heads off (again )

If you're running 18psi, you're already working on blowing the heads off.