subfloor@centurytrans

That's your problem right there - I came to the conclusion that NGK plugs were crap in an LS7 when I once had engine knock at friggin idle.

Put stock plugs back in and you'll be fine, but if I'm wrong I'll buy them from you and pay for shipping.

TTHIEL1@gmail.com

I will try anything at this point. Thanks for the advice!

subfloor@centurytrans

Good luck.

double06

Check to see that the rockers are not hitting the valve cover or the head valve cover rail. It may not be a height issue but more of a hitting the side or head issue. The problem with aluminum is it can take up a lot of room versus steel.

encasedmetal

plenty of us utilize ngk plugs. they, like any plug, have to be gapped appropriately for the setup. 0.040 gap on ngk tr6 plugs does not work on my car, but 0.045 sure does

freddyvette

Did you measure the push rods?