1fastssnova

I'm building an LQ4 with a Procharger P1-SC. I originally purchased LS3 heads from GMPP part# 12629063 - your standard non-cnc factory head. I was going to swap out the valves, springs and hardware for better stuff to deal with the boost.

These part#'s in particular from GMPP:

12605223 - 2.165" Intake Valve, 8mm Stem, Solid Stem, LS 15 Degree

12612427 - LY6 1.59 High Temperature Heavy Duty Inconel Exhaust Valve

Then, I found the LSA cylinder head assembly and thought maybe I should just use these with only a valve spring change.

12626958 - GMPP LSA Cylinder Head Assembly

I have found the 12605223 as a direct replacement for the LSA head intake valve, but I can not confirm that 12612427 is the exhaust valve used in the LSA head assembly. I don't know why GM would list all the part for this cylinder head but not the exhaust valve - it only says "Premium steel intake and exhaust valves"

I like the LSA heads because they are made with the roto-cast method and use a better alloy for boosted applications - if I can confirm the exhaust valve from the factory is the GMPP inconel one I listed above then I would say it's worth it to go for these heads.

Otherwise I will just keep my LS3's and change hardware - has anyone else come across this?? Thanks

1fastssnova

No body has anything on this - I can't be the first to have looked in to these part #s?

rotary1307cc

iTrader: (5)

No way they are iconel stock or Richard wouldn't have changed mine to SS

Here is what stock take off LSA looks like

rotary1307cc

iTrader: (5)

They are a nice stock casting though, look at that chamber finish

68 SS

iTrader: (23)

I agree, mine were just a standard steel valve they are not inconel stock.

1fastssnova

I don't get it, why would GMPP make a specfic part number for an Inconel valve, and not use it in the LSA head? In the GMPP catalog, they specifically list that above part number for the intake valve as a direct replacement for the LSA head, but nothing for the exhaust. Well I already have the LS3 heads so I'll prob just change the valves for the blower, and use the matched kit from Comp for the springs, locks and retainers. I mean I like the fact that the LSA's use the roto casting and diff alloy, but how many guys are running boost on LS3 heads with no issues? Head studs and a good MLS head gasket should be good for a P1-SC and 12-14psi, right? Any input and/or info is appreciated - thanks

68 SS

iTrader: (23)

If it was me I would Ditch the LS3 heads and get yourself a set of LSA heads and don't look back, they are way stronger and a much better choice for boost as that is what they are designed for.

1fastssnova

That's what I was thinking 68SS. Go for the LSA's and even change out the exhaust valve to an inconel just to be safe.