In the previous article on rocker stands, and as a general theme to the subject of pushrod valvetrains, the importance of stiffness was stressed. Also important though is that the mechanism is set up on the engine as intended when designed. This means that the relationship between the tip of the valve, the roller tip and rocker pivot are as designed. Not only does a badly set-up mechanism deviate away from the designed valve lift profile, but the relationship of the contact between the...

The question of valve material selection has been discussed before in the RET-Monitor. Much of the motivation for a given selection is provided by the operating conditions in which the valve must operate. Some materials are not suited for very high temperature use while others are too dense to be used in conjunction with very extreme valve lift profiles. In previous articles, we have looked mainly at the different classes of material with a view to having the valves made in a certain...