You gotta see this ......

Not pretty!

Seen it before on the younger brothers 340 in the late 80's. Gotta wonder why stamped rockers with the eddy heads? What cam and springs are you using.

Back then it was low octane on a high compression 340 and his lack of easing up on the foot when the pinging started. ( likely my bad for not curving his dizzy). This came first then 2 pistons in 3 pieces next. New slugs a little honing and a beat over the head for better fuel and it never happened again (along with re-curve). Brings back old days! Sorry for the misfortune, but speed and knowledge cost money!