I use a caged Torrington needle bearing with a 9/16" inside diameter, and make a sleeve for the distributor shaft from air hardening drill rod, ground to a very close fit to the bearing rollers. The process of heating the sleeve for a shrink fit onto the shaft also hardens it. If a final adjustment for fitting purposed id needed, I use a tool post grinder on the sleeve. The result is a zero-wobble upper bearing that will last about three days past forever as long as it gets a small shot of grease once a year.
Jerry
