On Mar 19, 5:23*pm, Stanley Schaefer wrote:

One question is why two cylinders would drop valves at the
same time.

Two possibilities come to mind:

1) Running out of oil (or badly overheating) might cause more than one
valve to stick in the guides fairly quickly.

2) Timing chain/belt skipped, throwing the timing off enough for 2
cylinders to crash (though I would have expected the same from all 4
if 2 went, maybe I'm missing something).