[Tom Goldman]

I do some driveline work for a shop that specializes in Packards and they started experiencing valve seat wear similar to this many years ago .
They believe its due to heat generated by modern day gas having a much different burn rate than gas of the '30's.
Engine cooling also is effected by the use of glycol coolant as opposed to the alcohol mix that was used back then. It may not overheat ,but the dissipation rate is different .
They now use Evans Coolant in these type of cars
They install hardened seats in everything now and have no problems .
Also if the tappet face is worn or has not been resurfaced properly the valve may not be rotating.
X2 on Billy's suggestion , Marvel defiantly helps on these old engines ,especially the valve guides.