High Quality Content by WIKIPEDIA articles! The Chevrolet Corvair engine is a flat-six (or boxer) piston engine that was used in the 1960s Chevrolet Corvair automobile. It was a highly unusual engine for General Motors: It was air-cooled, used a flat design, with aluminum heads (incorporating integral intake manifolds) and crankcase, with individual iron cylinder barrels. The heads were modeled after the standard Chevrolet overhead valve design, with large valves operated by rocker arms, actuated by pushrods run off a 9 lobe camshaft (due to the unique engine layout, exhaust lobes operated valves on *both* sides of the engine), running directly in the crankcase bore without an inserted bearing, operating hydraulic valve lifters, as used on most Chevrolet OHV engines.