Well as you all know last week I raced a cobra, beat it and limped home with a knocking engine, well i went through the valvetrain and set it up again, nothing looked out of order after re tourquing the rockers, then i fire it up and BAM the same knock is there, it sounds like it's on top of the motor on both sides but it's NOT a loose rocker, i did notice that after the run on sunday the collectors are blued...what does that mean? I know it's normal for the primaries to turn blue but The collectors were chrome even after the dyno tune redlines and just sunday it happened...