It is the little things that matter. You spend time and money for new points, plugs, filters, and take the time to get the timing and air mix right. So now it would seem to make sense to keep all that stable for as long as you can. The shaft in the dizzy has maybe the worst lubrication system ever. The lower part is splashed with oil, sort of. The top, and middle are.....dry. Grease from that cup is all there is. A sloppy bushing at the top of the housing will let the shaft wander all over the place. A little spring pressure will take that away. So for stable timing, and dwell, along with consistent point gap that spring is a cheap and easy fix. The disk/felt washer keeps the spring off the shaft. The "loose" fit of the washer/felt disk lets the grease do its job. Cheap, reliable, and it works. Win, win all around. Phenolic, nylon, or felt, all it does is keep the pressure on the shaft and the spring off.
