1. Glossary of Camshaft Related Terms
(Camshafts/Camshaft Information)

... cam lobe from the base circle (full lift position).   OHC: Overhead cam engine. In this type engine the camshaft is positioned above the valves. DOHC, double over head cam, SOHC, single over head ...

2. Sole Purpose of Degreeing Your Cam
(Camshafts/Camshaft Information)

... the crankshaft is miss-indexed. On SOHC & DOHC engines, milling the head or the block will retard the cam(s) On SOHC rocker arm style engines, valve tip length, rocker geometry and base circle ...