13 You can use shims between the pedestals and the rocker shaft to raise the pivot point. Ideally, you want the tip of the rocker to be centered over the top of its valve’s stem through its entire travel. Side Note: Here’s an example of why going cheap can cost you in the long run. These are a set of no-name rockers purchased off of a certain internet auction site that shall remain unnamed. The rocker arms are too short, so even though there are thick shims underneath the rocker shaft, there’s no way to get the roller tip centered over the top of the valve stem. This engine will run, but the misaligned rockers will side-load the valves.