Cam gone flat? Here's a interesting video.

Offenhauser race motors that ran at Indy in the 50’s and 60’s were overhead camshaft, with the cams having a hole gun drilled through the length of the cam. Engine oil was pressure fed into that passage. There were a pair of connecting holes drilled in the lob just ahead of the point of max valve lift to deliver oil to the lifter - lob interface.