Compensated Cam

The type of cam used to open the breaker points in a magneto installed on a high-performance radial engine. The master and link rod arrangement used in a radial engine causes the pistons in the different cylinders to be a different linear distance from the top of their stroke for the same angular displacement of the crankshaft relative to top dead center. A compensated cam has one lobe for each cylinder, and these lobes are not all the same. The difference in the lobes causes the breaker points to open when the piston in each cylinder is the same linear distance from the top of its stroke.