In the early 1950's the most popular original camshaft designers were the legendary Ed Winfield, the father of hotrodding, and Cliff Collins of Harman-Collins. There were lots of cam grinders that copied Winfield and Harman-Collins cams, but these two were the designers and innovators in the early days. It was popular to refer to cams as a 1/2 Race or Semi grind and a Full Race grind. Later, there was a call for an intermediate grind between these two. To fill this demand, Ed Winfield took the intake lobe from his full race cam and the exhaust lobe from his semi cam and called it a 3/4 Race cam (see Flathead Performance Cams). It was literally half way between a full race and 1/2 race cam.
Since that time, 3/4 Race has become a generic term for a high performance street cam, i.e. something less than a race cam.
