overhead cam

Short definition from Wiktionary

Noun

1. 1
   A type of cam (and camshaft) in an internal combustion engine, and thus also (metonymic) the type of valvetrain design, the type of engine that uses it, or an instance of such an engine; this design has the inlet and exhaust valves in the cylinder head and has the camshaft(s) up above the valves too.