its from the governer working back and forth I dont think I have ever taken 1 apart that didnt have that to some extendt and we do a lot of them and it doesnt seem to effect anything

70 duster full chassis super pro 416 CNC Indybrock heads 727 w/brake

best so far 1.212 60 6.219 in 1/8 at 110.88 9.768 at 137.81 1/4