--New Advice--
My local gurus are coming to the same conclusion, upon examining the head, cams and buckets. They say it's a clearance issue, not an oil starvation issue. Cam bearings would have gone first, if I'd run low on oil, but they're in better shape than the lobes and buckets that disintegrated.
No clearance, or clearance too tight, means that oil can't get to the contact surface, between cam and bucket. Erosion is said to inevitable.
I had just re-shimmed all the valves, before this happened. I thought I had it right, but I might have been wrong about a couple of clearances.
Anyone heard of this happening..?
Mark
-skidZmark-
