C4B4the04

Gents,

I think I have a set of LS6 Z heads. I have a 99% reason to believe they are as advertized and off of a Z but I don't know how to tell what year.

Facts:
They say 5.7 in the casting. That means they were off of a NON LS-2 engine, right? LS6's were the only motors that had 243 heads AND that displacement, correct?


Question:
There is an 03 prominently stamped in the casting on the underside of the intake runners on both heads, but there is also an 05 in a circle with 7 segments around it on one head, the other is a 13 with seven segments. Most likely the 5 and 13 are shift codes, but I can't tell if either one of those are date codes. 03 would obviously make it an LS6 set, with the light valves. Somebody put aftermarket springs (looks like 918's) on there, so that doesn't help. If they are 05 they are the heavy hardware and not a very good bargain for what I gave for them. Was told they were off of a 2002 but I don't see any 02 anywhere on them.


Before I worry, HELP!
Thanks in advance. Any help would be appreciated.

Cassidy

k24556

243 heads were put on ls2's and there are posts in the c6 section of the forum where members found one 243 and one 799. So the heads are interchangeable. That means you may not have the sodium filled valves, as they weren't used on the ls2. The only way to tell is to take the valves out of the heads and weigh them. There may be another way to tell,but I do not know it.

If you paid less than $450, you probably did OK. The non sodium valves should give you OK service if you put a little better spring in (not knowing your proposed mods)

C4B4the04

I'll swing by the parts store tonight and buy a valve tool. I have an 853 head, which should have the same valves as a non LS6 243 head and I'll weight the difference.

I have no reason to believe the fella was untrue about the fact they are the real deal, but I was hoping to verify based on the casting numbers. I designed the valvetrain around the idea of a very light valve.

Thanks, if anyone has any pics of the underside of a KNOWN year head with casting marks I would be grateful.

Cassidy

C4B4the04

FWIW in the future, there is VERY little info between here and the other big LS forum about date stamps in the castings on SPM cast heads.

I disassembled the valves today and weighed them. 71.4 intake and 64.9 exhaust. They are hollow and gas filled, respectively.

I did in fact buy a set of LS6 heads off of a Z06 and I am 99.9 sure that the number systems are for the years. For example, the 03 that is underlined in the casting is for 2003 and the 04 that I saw Steve Doten post a few years back similarly was off of an 04. Further supporting this, the bar code sticker at the back of the head on my setup starts with a K03 and his started with a K04 AND the dot matrix type numbers on mine start with 3, his with 4. They do seem to be year specific. Too many coincidences.

Well, that's my 23.5 cents on the story. If you ever find this post years from now, maybe you can update with your own experience. After combing through literally hundreds of posts, this is the best I could find.

Cassidy