[Tommy]

Those pistons look similar to the #2 & #3 pistons on my 351 Windsor with Edelbrock Victor Jr. Heads when it failed with about 3,000 miles on it. I was running 10.5:1 compression and I couldn't rule out detonation because I couldn't hear anything over the sound of the side exhaust. The only other thing that might have contributed to my engine failure was a small vacuum leak in the intake manifold creating a lean condition for the two failed pistons.

When I rebuilt the engine, I went to forged pistons and a slightly lower compression ratio (9.8:1). I also installed a knock sensor with a visual display to warn me of detonation. I've got a couple thousand miles on the latest build including some very hard track time. So far, so good.

By the way, be sure and check the valve train above those failed pistons. Those missing pieces had to exit via a valve.