I found this somewhere.
It comes from a guy named Ed Winfield. He started out making motorcycle cams with individual lobes pinned to a shaft. When he first made automotive camshafts, he was using a homemade cam grinder his mother gave him the money to buy. It was a grinder he converted into a cam grind machine by adding a rocker table. He reground Ford Model T camshafts into racing specifications. At first, he first made only two masters... a SEMI race and a FULL race grind. He later made a 3rd master that had more duration and lift than the SEMI but less than the FULL. He then used the FULL race master as an intake and the new master as an exhaust. He called this new reground camshaft a 3/4 race cam. He said it was three quarters of the way to a full race cam. He worked with the then famous Miller Racing engines and later with Offenhauser.
