Riding the back of the cam, meaning since the lash was too tight the rocker pad would ride on the "uphill" side of the base circle where one would expect little to no follower contact since the valve should be closed?
Speaking of burned valves, it made me think of a friend's valve guide I recently saw. '87 3.2 with 170K that doesn't use hardly any oil (surprising) & had a previous top end around 2000 with 100K on the clock. So I would guess this picture is a case of the guide being starved of oil from stem seals that do too good of a job sealing the stem? Sorry to hijack but just thought i'd ask your opinion.
