http://forums.corvetteforum.com/show....php?t=1915719

Does anybody know if these heads for sale are really LS6 heads. Isn't there a GM part number stamped on the end of the head?
LS6 Head GM part #12564824
Will these work with a FAST 90/90 on my LS1? Going to be doing a cam swap soon and looking at these heads. Price is good if they are real LS6 heads. Comments?

 

I run Ls2 heads on my ls1 car.Unless you are really going for HUGE HP #'s,I think those 243 castings are a good head for your car even if they are ls2 heads.As stated,the only real difference is the light weight valves,the castings are the same.

I also learned something by reading that thread,and I'm glad I have ls2 heads and not ls6 heads at this point.I have the correct length pushrods for my application...stock 7.4's

 

I researched this a lot and from what I've read, there's now way to tell by looking at the heads. You have to weigh a valve. I have a bunch of bookmarks and info on this at home and I'll post it up here later.

Brand new 243 castings with the light weight valves and yellow springs go for about $700 PER head from places like GM Parts House IIRC. So if those were "real" LS6 heads that would be a great deal. If they are LS2 heads... not so much.

I thought it was a great deal when I bought mine from frczwannabe a year ago. In the for sale thread he specifically stated that they came with the sodium filled valves. I let them sit for a year without installing them. Then recently I read over at ls1tech.com how a bunch of people had been scammed on ebay being sold LS2 heads (solid valves) as LS6 heads with the light weight valves. So I borrowed a valve spring compressor from Pep Boys, pulled a valve and weighed it. It was 100g for an intake valve which means LS2 heads

Again, there are threads on this at ls1tech. The only sure fire way mentioned to ID them is to weigh a valve. I saw some mention of the colored paint marks on the bottom of the valves possibly indicating what valves they are, but no one knew what color meant what. BTW, if anyone thinks $600 for new, complete LS2 heads is a good deal, I'll sell you some at that price

 

May want to check what year heads you have.

From an interview with GM design folks: "The ’01 intake weighed 99 grams but the ’02 weighs only 76. The ’01 exhaust weighed 86 grams but the ’02 exhaust weighs 63 grams."

source: http://www.idavette.net/hib/02ls6/page2.htm

 

Wow. I had no idea people actually fussed like this over the hollow valves.


I would have to think any big head porting shop would have bins of those things laying around, as most ported/performance 243 heads are running larger-than-stock valves anyways.

I guess if you want to pay more for the special valves, that's cool....but if it's a 243 casting, then it is a REAL LS6 head, period. Just because one person feels that the light valves are implied by calling them LS6 heads, apparently forgot the LS6 was produced in 2001 too.

First thing I'd do with a stock set of 243s is strip them bare, mill them, port them, then load them with 2.04/1.57" valves.

 

It's matter of getting what you pay for. The list price of the LS6 heads with light weight valves (GM part# 12564824) is $1,070 per head. The LS2 heads (GM part# 12576063) list for $425.71 per heads. Obviously, hollow intake valves and sodium filled exhaust valve aren't cheap. Sure they aren't worth more to someone who is going to CNC the 243 casting and put in larger valves, but why would you buy a complete head if that was your intention?

GM didn't put the lightweight valves in there for no reason. Sure they won't do much for HP, but they will help the springs last longer. GM bumped up the cam for the '02-'04 Z06 and in order to avoid valve float and meet their durability requirements they moved to the stronger yellow springs, hollow intake valves, and sodium filled exhaust valves. Also, the light weight valves are longer as GM paired them with the smaller base circle on the '02-'04 Z06 cam. Technically you should run different length pushrods if you use the light weight valves with a typical LS engine sized cam.

How much horse power the lightweight valves are worth is not what I'm debating. I'm just saying, be sure you know what you're buying because some people are misrepresenting these heads.

 

They don't. Porters don't buy complete heads and throw away the valves to port them.

Who wouldn't want lighter valves? If you're on a budget and can get the light valves just a few bucks more, that would be cool.


If a 243 casting is a REAL LS6 head, than how come the LS2 motors come with them? Do LS2 motors not come with REAL LS2 heads? LS1, LS2, and LS6 refer to the motors, not complete heads. The actual cylinder heads are 243 castings. That's what they really are. The LS6 motor came with two different complete assembled heads, GM part# 12576063 & GM part# 12564824

Do people selling heads as LS6 heads apparently forget that 3 out of the 4 model years of LS6 motors came with the lightweight valves? Why don't they refer to them as LS6/LS2 heads to remove the ambiguity? When I bought LS6 heads I specifically asked the seller what valves were in them and he lied. Not much you can do about that, but the more people know about which heads are what, the better they can assess the value and risk of the purchase.


Yeah, and you'd probably buy bare 243s which can be had from several forum vendors for less than $400 if you were going to do that.

 

I just realized why people aren't seeing this as misleading as I am. Here's how I see it, please correct me if I'm wrong.

243 castings WITH YELLOW VALVE SPRINGS were never put on an '01 Z06 by GM. The 243 castings that came on the '01 Z06 had lesser valve springs that were not yellow. 243 castings on LS2 motors did come with yellow valve springs (and other colors too I believe), but all all of those have the solid valves. The only LS6 motors whose cylinder heads came with yellow valve springs are the '02-'04 Z06s which had the lighter valves with the longer valve stems.

So if you're calling 243 castings with yellow valve springs LS6 heads, they should have the light weight valves to be REAL LS6 heads (ie as supplied by GM).

 

I thought the LS6 243 heads had the lighter hollow sodium filled valves & titanium springs ( to rev higher) and the LS2 243 heads had the normal solid valves and steel springs?

 

243 is a casting number. Depending upon the year and motor they were installed on, you may get different valve train components.

2001 Z06 had 243 heads, stock dimension and weight valves.
2002-2004 had 243 heads with longer, hollow valves and upgraded springs to handle additional lift and RPM.
LS2 motors also use 243 casting heads and standard valves and springs.

 

Man knows what he is talking about... bump for you PAT, GOOD LUCK ON THE NEW H.P. Tell me how it ends up...

 

Titanium springs?
For $60/set?

You can't buy stamped Ti retainers for that cheap...I'd hate to see what a spring made of Ti would cost...$several thousand no doubt.

Anyways, the LS2/LS6 (yellow) spring is the same part # (12586484).



As for revving higher, it's curious that the LS2 reverted back to the heavy,solid valves, yet retained the same 6500 redline as the LS6.

 

yah $60 for titanium springs seams a bit cheap. Maybe that was $60 a millimeter.

 

Yes but they also went back to a cam with only .525 lift.

 

The LS2 also reverted back to the 2001 LS6 cam that had 525 lift vs 550 lift and a more aggressive lobe profile for the 2002/2004 model years.The larger cam with lighter valves (better valve train stability) with springs capable of 570 lift would without a doubt out rev a LS2 day in and day out.

 

I have the later style '04 ls6 heads, and the machine shop is telling me I dont have the sodium valves, and that gm went away from them at the end of the year (cost)...does this sound right???!

Dustin

 

hey, Im kinda new to the Corvette crowd (hint the name)
I used to be a hardcore Ford guy...
got me a 2000 C5 vette, and now i need to make some power without adding any Forced Induction. reason being, its going to be my Road-racing track day car.

So, Can i stick LS6 heads and cam to my LS1?
I was checking GM performance, and read that both LS1 and LS6 blocks are the same... so instead of my spending money on LS1 heads/cam, I would just go buy LS6 stuff.

thanks.

 

LS6 cam and heads will fit in a LS1 just fine.

 

OK, I am thoroughly confused on the valves now. I am having the 243's installed on my car now, and I know they are the sodium valves. So, are my stock length pushrods wrong now? I haven't gotten the call from the installer saying anything was wrong yet (except when he called because he didn't like the way the milling looked so he took them to a shop he uses and one was 4 thousandths off in the middle), and I know he is checking ptv clearance, but are the sodium valves really longer than stock? The heads are off of an 01 Z06, and I am relatively sure the pushrods in that car are the same length as "normal" ls1 engines, hence my confusion.

 

The short story
The valves are different length, but not enough to make any difference.