Cwarta

iTrader: (12)

Well, I bought these cnc heads off a guy on here who swore by them, said they worked awesome and were a great bang for the buck. He sells me the heads, I get them and they look great, he "assembled " them and checked over the Q/C so like am idiot I didn't question them, I just bolted them into my 6.0 ls2. Car made goid power, h/c it put down 454/425 with a 231/240 duration cam. Car ran good, got about 2000 mikes on the motor and boom, dropped a valve.... Trashed everything .

This was about a year ago. I sent the heads off to have the heads fixed and chamber welded etc, and it needed a new guide. I sent them to midwest cylinder head, and they call me and tell me they can't put in new guides because they don't have the tooling. So I'm assuming you can't do LS heads? Oh no we do plenty of them, these heads have guides for oversized valve stems. What?!?? So I go out and sure as **** the valves that were in the heads were standard 8mm stems. So Appearentlyprocomp orthe ******** dealer I bought them from put in the wrong valves. So please if you buy assembled heads please check, I don't have exact numbers but the clearence was over 10X what it should have been.

So, we now have :
Cnc ls3 pro comp heads
New guides 8mm
New farrea 6000 series valves
New valve job
Hand ported further.
Decked .065

Hopefully they flow well to support this 416.....

KCS

iTrader: (20)

That's actually common on the aftermarket stuff, but usually a slightly smaller 5/16" (.313") diameter valve is used instead of the 8mm (.315"). It sounds like maybe 11/32" guides were used (.343").