Heres the situation: our 68 w/302 is still under body repair, but we do drive it around the block every now and again. Started it up last night to drain the flush stuff out of the engine, and it starts "clanking" on the passenger side. Got the timing light out...#1 plug fires intermitant. Pull the 1-4 plugs.../forums/images/icons/shocked.gif. #1 plug is black sooty...#2-#4 is clean (low milage since replace) #1 plug has some brown on 1/2 of the insulator, the other half black sooty. Manual says may be stuck or burnt valve? The "clanking" is a clank, not a ping or "tap". Pulled the valve cover....nothing unusual. Collapsed lifter, broken lifter, bent rod, broken valve stem? Suppose I should start by pulling the top end apart or pull the pan and look at the connecting rods/bearing caps? I pulled the heads while replacing the timing chain last summer. Compression check was good and no cylinder ridges last year.Prolly put a whopping 50 miles on it since then. It was all in working order last week! Honestly!