After the QP thread, I thought I would start this.
When I rebuilt the 389 in my wagon I found the piston below. It reminded me of a story an old Chevy service Mgr told me. Before he was Mgr a lady brought in a '71 big car wagon she had bought there. She was complaining about a rattling noise in the engine. By the time it got to him, they had already ordered her a counter replacement. When it came time to put it in, he got the job. He said, "Everybody get out of here.", making all the guys leave the bays. He got in the car & floored it for a while. Eventually the flagging from the manifold casting blew out the valve. He sent the car back to the happy owner, and they gave him the replacement motor.
Mine looks like a choke housing screw to me.
What you guys got?