Was cleaning bottom of intake and found 5 of these hard plastic beads , in the draft tube outlet, also some black stuff ( probably old oil) smeared on the inside that had what looked like grooves the same size as the balls. One pic shows 3 of the balls and the other pic shows the black . Are these large blasting or polishing. Beads?
There used to be a process named Extrude Hone that used a very thick black abrasive paste. This paste was pumped back and forth through chambers or tubes to smooth, polish, deburr, radius edges of both the interior and external surfaces. I think it was also used to improve and polish exterior surfaces. I know it was also used to port and polish intake manifolds. Don’t know if process used balls as shown but seem reasonable it might have.
Or maybe a kid put them in there. I know I shot plastic darts into the gas tank of my dad’s ‘60 Valiant when I was 4 years old. He put some darts in a jar of gas and when they didn’t dissolve he decided to leave the darts in the tank.