Originally Posted by Casey_SS

Thanks Bret...I was hoping you'd chime in on this one

I thought about the oil pressure aspect as well and here's what I did about it...feel free to troubleshoot my logic:
- cleaned lifters with mineral spirits, dried 'em and soaked overnight in clean oil
- pulled them one at a time out of the oil and straight into the lifter bores
- set lash to half a turn and let intake RTV cure for 24 hours
- started it, let it warm all the way up and revved it to ~3k a few times to get some oil pressure in them
- valvetrain was very "clacky" sounding and was getting lots of knock retard when revving it
- reset to 3/4 turn using same IC/EO method, poured fresh oil over rockers - better but same issues as above
- reset to full turn doing everything the same and it sounds "stockishly" quiet now but still getting intermittent knock retard after 100 or so miles. KR has never been an issue with this car in the past. I've had the rockers / springs installed for well over a year with no KR issues. Only real change is the lifters - I started getting some KR when my stock lifter began ticking and I can't seem to get these new ones quiet enough to make it go away.

Thoughts / recommendations? Not sure where to go from here...gonna try some race gas this weekend to rule out any real knock but I'm not expecting any change from that. Pretty sure it's the valvetrain pissing off the sensor. BTW, it's an LT4 KM, OBDII tune by Ion with his standard KS desensitization.