i was just driving normal and i heard a ping, then clack clack clack. so i shut the car off and got it home on a flatbed. i pulled the oil pan, nothing bad down there, pulled the cams out, no broken springs. then i pulled the head off and this is what i saw. dont know what caused it because there was nothing in the cylinder and it was only that one that has the marks in it. the plug is good. anyone have any ideas?