With a conventional direct-acting valve train, the maximum lift is usually determined by the size/diameter of the valve lifter. Selecting a high-lift camshaft without taking this into consideration often results in the camshaft lobes travelling beyond the surface of the valve lifter. This causes the lobe to make contact with the edge of the lifter, damaging both components over time. (see fig. ②)
Therefore, the ideal performance orientated high-lift camshaft needs to have a profile that maximizes lobe travel on the lifter without exceeding the outer edge.
VALC profile camshafts have achieved this ideal by deliberately reducing the maximum cam velocity to limit lobe travel on the lifter surface. (Maximum cam velocity = lobe travel distance on lifter)