Allen,

I only talked to you for 30 seconds at the track a while ago but I will say a few things anyway.

There must be problems with L92 (and other engines with AFM) lifters 'cause there are TSB's on them. The document speaks of failed AFM lifters. I've seen none in person.....yet.

I still have a 2007 non-AFM 6.0 with a junk cam (no cams available in the GM parts chain) waiting for parts. During my diagnosis of an engine noise that only happened at 1650 and 2400 RPM (at an audible level) I found that within less than 5 minutes of the engine running, ALL lifters would bleed down enough to close all valves on one head. What's really weird about that? I could pry the valves open with a screw driver in the stock rocker arm and it would not fully close when pressure was released.

Weird indeed.