The Opel Cam-In-Head engine ("CIH" for short) is a series of inline engines which was built from 1965 until 1995 and was available in four- or six-cylinder configurations. Its name derives from the location of the camshaft, which was a compromise between an overhead valve and an overhead cam layout. The camshaft was mounted above the cylinder but aside the valves and actuated them through a very short tappet and a rocker arm, as it was not near enough to act directly upon the valves.