Lost Two Gen 3 LS Engines in my 1986 C10 2WD

[Ricko1966]

Thing is that I watched cylinder #2 intake valve closing very slowly when turning over after the damage had occurred. That's what led me to believe it was valve to piston contact.

The other thing that strikes me as odd is that it ran good when I shut it off. It's the next time I went to start it, it turned over super easy, so either the damage occurred as I shut it off (which doesn't coincide with injectors filling the cylinders while running) or the starter damaged the motor? Just doesn't seem likely to me

See if all the pistons are parking at the same height,check through the spark plug holes.

 

[Ricko1966]

Here's something else to think about. When you tag a valve it's usualy an exhaust valve,because the piston is chasing the exhaust valve shut. The intakes are opening as the piston is moving away from them. I'd takethat engine apart and investigate. At the least I'd see if all the pistons are parking at the same height and pull the rockers on the low cylinders and manually open the valves feeling for binding opening and watching for binding closing., and usually a bent valve will park at a different installed height.