Can someone explain this port please

My Dad (passed away in January of 1984) dropped a machine screw down into the intake of the 440 in his 62 Dodge convertible. He thought just starting the motor and running it would blow it out the exhaust. It didn't. I pulled the driver's side head (can't remember how I figured out which one to remove), and the screw was imbedded in one of the OEM cast pistons. I pulled the screw out. The piston had screw thread marks in it, but otherwise seemed OK. Buttoned everything back up and ran it that way. The piston never failed.

Some time later he dropped an exhaust valve in his Hemi Charger. Then drove it five miles home. The valve head was imbedded in one of the pistons, and had knocked a hole in that head. Then he gave the car to me.

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