COPOSS

They have the same casting #'s 243. But the Z06 has the D shaped exhaust runners and the 243's off the GTO are O shaped. I read that the D shaped runners are a better performer than the O shaped off the GTO.Is there a difference ? And if i get a set off a GTO will it be worth it? Or get a set off a Z06.

BAD2000TA

iTrader: (6)

The GTO castings also have the D shaped exhuast ports. Usually, you can't tell because the exhaust manifold is circular and the black carbon covers the "d" portion.

The only difference between the two are the exhaust valves. True Z06 heads would have sodium filled exhaust valves. Springs in the 2002-2004 are rated to .550 lift, where LS2 are rated for .525.

COPOSS

This is the 4th time i have seen this on Ebay. And it was a clear picture of the exhaust.It must be the carbon. Thanks!!

VIPRETR2

iTrader: (63)

Also the Z06/LS6 heads have hollow intake valves.

redtail2426

iTrader: (10)

you guys are all right,heads themselves identical except for the hollow intake valves and sodium filled exhaust valves on the z06....But here somthething else..The z06 valves are also a little longer which means they reguire different length pushrods then any other head.I cant remember how much longer.

VIPRETR2

iTrader: (63)

I remember reading something about that on here. I'm using the same pushrods I got in my Thunder Racing cam kit for my LS1 in my LS6. Seems to be working real nice and no extra noise or anything. Something to research, I'm not too concerned with it myself.

Larry

itslow

iTrader: (4)

FYI: The 2004 LS1 GTO did not have 243 heads; only the 2005/6 LS2 GTOs did.

RZRSEDGE

iTrader: (21)

I think he was referring to the LS2 Goat heads.

LS1W66

I thought I read that the Base circle of the `02 Up cam is smaller and thats why the valves are longer ?

01Z0H6

iTrader: (63)

I am currently running a pair of unported LS6's out of an 05 GTO... Purchased them from a friend when i mucked up my LS6's out of a Z06.

They are the same from what i can tell.

99ssleeper

iTrader: (98)

Since the LS2s are a 4" bore, wouldn't the combustion chambers be slightly larger?

muncie21

iTrader: (14)

That's true, but the difference in size is very minor. No issues running a Z06 cam in a stock LS1 or Z06 heads on a LS1 motor.

99ssleeper

iTrader: (98)

Just so LS1W66 has all the info...it is true you can run the cams in an LS1 but you should also alter the pushrod length to accomodate. The base circle is .050" smaller which is significant. By putting the later LS6 cam in an LS1, you should run a .025" longer pushrod. Some do, some don't.

muncie21

iTrader: (14)

I never figured 25/1000's to be significant with hydraulic lifters. But to each his own. I have a Z06 cam in my motor and it's as quiet as the factory one.

99ssleeper

iTrader: (98)

I know, I'm only posting it so all the info is out there. Some people care about those things and some don't. I haven't read about any ill effects of not swapping pushrods.