f6john

Is there a specific casting number to look for when looking at 243 heads?

Vetteman Jack

Would be good info to know.

cqd24

243 is on my Z06 heads, hope that helps!

f6john

Not really, all C5 Z06 heads are 243's but not all 243's are Z06 spec heads.

RSbeast

The only thing specific to c5z 243s are the valves and valve springs.

The springs are junk anyhow. I believe the sodium valves are a different color.

f6john

Some of the reasons I am inquiring about casting numbers or anything else that would be a singular identifier.

chassed

Specific to what? Seems like you answered your own question..?

chassed

243's came on the LS6 and LS2 6.0..

f6john

Ok, let's try the question this way. Someone, anyone, says, "I have some Z06 heads for sale." Is there a casting number or other specific marking or characteristic that would confirm they were originally installed on a Z06?

k24556

No. the parts manual shows the bare head with valve guides, seats and plugs. It does not show the head with a part number for the assembled head. 799 heads can still be sourced, but they are getting very scarce. They are basically the same as a 243 head.

The 04-06 Caddy CTS-V had the LS6 engine, 243 heads, but I don't think it had the sodium-filled valves. My 07 CTS-V had the LS-2 and I have one 799 head and one 243 head, never been changed.

Now, the last C5 Z06 with the desired heads rolled off the assembly line over 11 years ago. Unless the "Z06 Heads" were pulled off a garage queen Z, you have no way of knowing the history of the heads. About the only reason a set of heads gets separated from the engine [for sale] is sumpin' bad happened down low.

That means it is likely there is some latent damage to the heads, bent valves, metal shavings in the oil galleys, etc.

I am guessing you are looking for heads so you can mod your LS1. The LS1 in current state is a $2k value. The mods another $5k. Those "Z06 heads" really need to be gone through by a good machine shop. At the least the springs need changing and each valve inspected, plus a thorough run thru the hot tank for cleaning. I wouldn't risk $7k for a set of heads worth $400-450

So bottom line, it does not matter if they are "Z06". They need to be gone through anyway.

f6john

Thanks for the info. I'm not actively looking to replace my heads at this point but occasionally see some 243's for sale that get me thinking. It pays to be well informed.

k24556

I put a set of 799 heads on my Y2kFRC when I modded the engine. They came of a 2006 Trailblazer SS, and I know the engine suffered a spun rod bearing. During cleaning, the shop found shavings in the he galley, and the shop boiled the heads several times before declaring victory. After that, the valves were fine and he just reground the seats and valves and faced the stem tips to get the correct deck height. Been lots of hard miles since, but a good shop will give you an honest answer.

I gave up worrying about having sodium filled valves. My butt-o-meter is not accurate enough to tell the diff. I do know I DO NOT have them.

This shop does a lot of high performance stuff, and I trusted the feedback I got. He said he would use them on a high performance LS that he knew was going to get pounded on the track. Since I cammed, I wanted to make sure I had the proper PTV clearance. Lots of ways to measure, modeling clay, etc. The machine shop put some "check springs" which are very light temporary springs just for checking PTV. A good relationship with the shop and he worked with me, loaning the springs and putting them in for me so I could do the checks.

So, a suggestion, first find a shop that does that kind of stuff and one you are comfortable with. Then when you find some heads, make the sale contingent on the inspection by the shop.

momo20

my brother has 799 heads which came on his l33 which he swapped out his ls1 in his 2002 camaro z/28 in a sorta forced upgraded and the L33 came with the 799 heads which are more or less the same as the 243 heads from what i have read

Johnny wangwang

243 and 799 are just the casting. In order to check and see if you have 2002-04 Z06 243 heads (not sure if 01 Z's had the special valves) you have to physically remove the valves and weigh them. You cant just look at them and tell. If you can find a set with the right valves then get them. But normally they go for a little more money if people know.

f6john

Are all 243/799 heads cast exactly the same? Port shape and valve sizes the same? Also wondering about differences between 241 castings and 243 castings.

k24556

See if the attached helps. Don't know the source, I've had this doc for some time.

The CC of a 241 is much bigger than a 243.
243/799's are the same. As I posted earlier, my 07 CTS-V with an LS2 has a 243 on one side and a 799 on the other. And they have NEVER been off the engine. Came from the factory like that. Since the engine has 105k miles, and still runs like a striped-haint, I guess they are close to the same.

f6john

Thanks, lot of good info there.