Ls6 cylinder heads

[RollTide696]

This may be a dumb question about 799 heads. Are all 799 heads the same with that casting number? My buddy has a 4.8 liter LS motor out of this G van with 799 heads on it but I find it hard to believe that this motor came with the same heads as an LS6. Any information would be greatly appreciated.

[SMWS6TA]

They are the same casting. What is different is the valves and where it was cast. 243's had sodium filled valves, 799's did not.

[pajeff02]

Welcome to the site, Aaron.

[SMWS6TA]

I should also add that not all 243's cam with the sodium filled valves. Only on Vettes did they come with them.

[Firebirdjones]

Yeah alot of confusion over the years. The "real" LS6 243 heads had the hollow stem sodium filled valves that were light weight, different springs, and also had redesigned combustion chambers that are said to be extremely efficient. They are a cylinder head in their own league and only produced from 2001-2004 on the Z06 vette.

Other 243's seen on some LS2's later in production don't have any of these features. The only thing they share in common are the 210cc intake and 75cc exhaust port sizes and D shape exhaust ports. Some other castings also shared the port configurations like the 317's and the 799's but they didn't have the same combustion chamber designs (317's bigger and 799's smaller and both with different shapes) which had a negative affect on flow and efficiency compared to the 243's. Comparisons on flow benches play that out.

So the 243's are unique from 01-04 and for the purist or hardcore, technically speaking, are the only LS6 heads while the others simply copied port designs.

[SMWS6TA]

I got lucky with mine. The seller claimed they were true 243's. The only way to tell if they are the true valves isvto weight them. Mine are the sodium filled valves.

So it's nice to know there are truthful sellers out there.

[RollTide696]

Awesome guys. Thanks for all the help with this.

[SMWS6TA]

If you are looking at a use set they usually go for around $400 for the pair. It will cost some $$ but have the looked at. I had an engine shop checked for cracks, surface level, replace the valve guides, clean up & lap the valves & setup the springs all for $185 (they didn't need resurfacing). He also verfied the valves were in fact sodium filled. If one valve was bad it would have been a major difference in cost of replacement.


If you do get these heads I recommend using ARP studs that are 6pt. Also make damn sure the head bolt holes are clean and fee of any coolant. Otherwise you'll be buying a new engine.

[RollTide696]

I would either go with a set of 243 heads or I might see about getting some 6.0 liter heads. Either of the two would be fine when I get to that stage of building this motor.