Engine Question

[Brettcobra]

I have what is reported to be a 2004 LS6 Corvette ZO6 motor and 6 speed box. The problem is that I can not reconcile the block numbers or head number to confirm authenticity. The block number I have ( assume casting No ) is 12550592. The numbers on the Heads are 243, 2215MK, 291024, 2507219.

I understand the 2004 engine has a part no of 12578104; is this number anywhere on the block?

The photos of the ZO6 engines over the last few years seem to vary, e.g. the alternator moves from bottom right to top right.

Can anyone assist?

Cheers Brett

[MsSchroder]

Brett,

Welcome to the CAC. I've looked around in the model center here, but can't find info about the 04's with that much detail.

There may be someone over at Z06vette.com who could help you out.

Tammy

[leaftye]

243's are Z06 heads. 241 & 853 for Corvette LS1 heads.

Much more information about the block & head numbers here:
http://www.ls1tech.com/forums/showthread.php?t=213148

[TODD L GRIFFITH]

The block has a casting number, a machined number and an assembly number. Casting number will be most likely 12561168.
Machined number will most likely be 12561167.
Assembly number will most likely be 122561166.
Note: All 03 and 04 LS1's used this block also lol!

The cylider heads have a bare casting number, mach casting number and an assembly number.
Bare casting number is 12564241.
Mach casting number is 12560800.
Assembly number is either 12560802, 12568315 or 12564824.

A giveaway that you have LS6 heads is a cast triangle under the exhaust port at the manifold between the head bolt bosses on the side of the cylinder heads.
The LS6 head also has "D" shaped exhaust ports, but will not be visible unless you remove the exhaust manifold.

Depending on when your car was manufacturered, these numbers are subject to change. Numbers posted above were gathered in 2003 and are from
S-A Design, Cartech Manual/ "How to Build High Performance Chevy LS1/LS6 V-8's"/ "Modifying and Tuning Gen III Engines for GM Cars & Pickups."

[c4c5specialist]

All that has to be done is the stamped number taken off the side of the block, near the drivers side.
It will have the last 8 digits, which will correspond to the vehicle the car was taken out of.
This will tell EXACTLY where it came from and what engine it is.
Allthebest, c4c5

[TODD L GRIFFITH]

http://members.aol.com/chevroletman/block.html

Just found this link. The casting number 12550592 refers to a 97' and up LS1. Yes, I found the same info, number is stamped behind the head on the drivers side where the bell housing meets the block.