I'm looking at a couple different sets of L92 heads to put on a LQ4 6.0L, just wondering what the difference might be between the casting #'s ? ie. casting # 823 vs. 821 ? Is there a physical or performance difference? Is there a casting I should stay away from for any reason?

Thanks!

 

I believe that functionally they are all the same.

Andrew

 

They are all good. Later heads went to rotocasting method.

 

821= LS3/ Hollow stem intake valve/ yellow beehive springs

823= L92/ Steel intake valve/ stock springs..

Some say the 821's have a smoother finish....

reality both are the same castings, and both had some not so smooth areas but in different locations.... Nothing crazy.... I did not even touch em(port em or polish em), I just popped em on... besides milling and spring kit....

Bozz

 

5364 IIRC from my 08 LY6

 

Is it #5364? I was thinking it was #3564. Either way the difference between these and the #823 are the #5364 were cast in green sand and have a smoother finish in the ports and combustion chambers. SLP grabs all of these smoother heads from production. I tried to get a set when I bought my #823's but they looked at me like I was stupid.