Subscribing. I was under the impression that these were non-interference engines. Maybe I'm wrong, but I would like to hear what caused the valve damage.

 

This is all very strange. Valves don't bend or come in contact with pistons because of a lean/rich condition, the timing chain would have to jump. Unless the valves are sticking in the guides. The only thing that could cause a valve to stick in the guide is no lubrication (oil supply) or some really far-out temperatures or crud building up on them.

This is all just plain weird.

Lean condition would burn the seat or the edge of the valve, not bend them.

 

Maybe the valve heads warped due to the lean condition? Would have liked to see pics of the pistons to see if there were any "witness' marks from valve contact.