Cams, above, live a harsh life. Although bathed in oil during operation, oil drains after shutdown, reducing corrosion protection.

by Jim Cavanagh

When you finally face the music and decide on an engine overhaul, there’s always a tense time between when the engine is sent out and when the shop calls with the good or bad news describing what they’ve found. In the fantasy world in which aircraft owners sometimes live, the shop calls and reports the cylinders are perfect, the case is like factory new and the cam is good for one more TBO run, at least.

In the real world, the cylinders are junk, the case is cracked and, oh, you’ll need a new cam, too. Although crankshafts get all the press—most of it bad, it seems—the cam is…