Bronze distributor shaft gear wear
I am amazed after 30 replies that nobody has mentioned the Melonized [ specially treated steel ] gear/shaft available from Hughes Engines for steel roller cams.
I started using the Mopar Performance [ then called Direct Connection ] 'performance' oil pump drive in the 70s. The shaft was 4X40 moly steel. It was NOT stronger than the case hardened stock shaft, but was easy to machine the taper at the hex, which was where the brittle non-tapered hex on the stock unit could snap off with high load from the oil pump.
This shaft created a new problem that Ch failed to tell folks about. The 4x40 steel is hard, not hardened. The bronze bush is very hard & will....&...did....wear the soft steel.
This is likely the cause of the wear in this case, not something else.
Some early engines used an alum bush, not bronze. I use these with the soft aftermarket shafts & neither the shaft nor bush will wear.