Was the bottom nylon busing in the pic installed in that same way? Almost looks like if you flipped it it would have tightened up to me. I do know when I spin them up when the weights extend it wants to raise the main shaft up and lowers it when the rpms drop down, Seriously think no plastic and it might have slapped down on the bushing, just a thought. I am not positive when the spiral started might have been when the oil cup was still going on I do know 66 and back are smooth for sure with a oil cup. Hmm great question, just like that large number on them when/what the hell is that for? No answers from any one yet on it! And they are not on all of them either!
