[Bruce Edwards]

Matt.

Drilling the rod and gear for a larger pin may cause a falure of the shaft. The pin is NOT the part that keeps the gear in place. It is a press fit the pin is just a safety device like a cotter pin on a tie rod or ball joint. If it is set up right the pin will never have any strain on it. There is a reason they call it a shear pin after all. If your distriburor is shearing pins the press fit may be to loose. Installing a larger pin will not fix the problem. If the shaft is torn up from shearing the pin you will need to start with a new distributor shaft.
I use HV/HP pumps in every motor I build. I have never had a distriburor fallure in 20+ years of building engines. The pump is not the problem.
If the distributor shaft is binding it will shear the pin. Did you ever pull the shaft and check the bushings in the housing or the condtion of the shaft at the bearing location?