The student of automotive history knows that there are no new ideas. Long before Chrysler engineers had the idea, the engine of the Pontiac, Michigan-built Welch featured hemispherical combustion chambers – a "Hemi" ahead of its time – with its valves in small "cages" and actuated by a single overhead camshaft, driven by a vertical shaft off the crankshaft, and rocker arms to a pair of inclined valves per cylinder. There are two spark plugs per cylinder, with ignition by trembler coils for start