Jon, the cam shaft is hollow. 70% of the pump oil is routed down the cam shaft and sprays out several small holes at the crank and piston rod bearings. They are splash lubed. At the back end of the motor, there are two small oil lines that lube the valve and rocker arms, and a little bit to the governor bearing up front. About 15% of the total oil supply goes to the filter and is drained back to the oil pan. Note that the filtered oil is not routed to the bearings like a car moter. Dont drill the crank. Spend your time and money getting the bearing clearances right. The motor is big, heavy, well designed, and built to run 50 years. Remember top speed is about 1600 RPM, not 4000.