I was just trying to help,in case it was something simple--I wasn't aware he'd already checked the valve train....I once had a 283 break a rocker arm and it went from a nice running engine that burned zero oil,to a rough running smoker in a matter of 5 minutes,I thought something serious had gone wrong,and was all set to swap in a 350 I had,till my brother suggested I do some investgation....turned out just one intake rocker snapped in two,and the push rod bent--easy fix for free,with used spare parts..................................................................................................I've had engines that closed up the plug gaps when carbon broke loose too,its not always a indicator of disaster...when I see splattered melted aluminum on a plug,then I'm pretty sure something BAD is going on in that cylinder...