u/Longjumping_Court580

What do you guys think is the cause of this? I got this engine which was supposed to be assembled and tested for compression and ready to go. It was supposed to be never started before. I went to start the cam break in and within 5 seconds heard some very awful noises. It’s a 383 stroker small block Chevy not that that matters.

Update: I have not found anything other than piston material, bearing material or piston ring material. I checked all main bearings they all seem fine. My guess is either they forgot to install the wrist pin retainer or something got in there, however I haven’t found what that something is.