Many gains in power and reliability in an engine can be achieved by careful building. When the rocker gear is installed, the rocker motion should result in the rocker being at 90° to the pedestal at half lift. To achieve this, the pedestal is either raised with shims, or the under face machined off. This exercise will invariably result in the push rod ball pins being out of adjustment, requiring different length push rods. These rods allow for a perfect length of pushrod to be achieved and are a must for any well built engine.