Automotive, motorcycle and marine overhead valve engines, as well as conventional prop aircraft engines, have used rocker arms as part of their valve train design for many decades. Roller tip rocker arms became part of aircraft engines not long after WWI, but roller tip aluminum rocker arms didn't come along until the late 1950s, and when they did, they were designed from a simple mistake that made their precision ground camshaft driving them, waste much of the information.

This is the story of how that mistake evolved, and what the difference between "conventional" and MID-LIFT roller rocker arms really is. This FREE document is a must have for any serious engine builder who needs to make informed decisions about the parts he or she chooses and how they are installed. History has always been a good porthole in the past for avoiding the same mistakes of the future, and nothing does a better job of pointing out a simple, albeit trivial matter of fact for a niche industry, as high performance engines has always been.