Influence of the cam shape on the forces
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The design of the cam shape has a very often vastly underestimated influence on the forces in the valve train. For clarification and comparison, a graph is shown below. Both cams produce the same lift and exactly the same timing. Even the slightest deviations in contour cause enormous differences in the load on the valve train.
In one case the rocker arm is loaded with only 207 kp (456 lbf) and in the other with 345 kp (760 lbf).
Therefore, the cam must be precisely calculated and manufactured!