http://en.wikipedia.org/wiki/Ford_Galaxie
Late in the year Ford introduced their new engine challenger, the SOHC 427 Cammer, Though not documented, it is believed a few may have found their way onto the street (this engine was only available to racers through the dealer network or from the manufacturer; none were ever factory installed). Rated at over 600 hp (447 kW), this is possibly the most powerful engine ever fitted to a production car by an American manufacturer. NASCAR changed the rules, however, requiring thousands (rather than hundreds) of production examples in service to qualify for the next season, and Ford decided against producing the Cammer in that quantity. Fears of liability concerns and the bad publicity possibilities in giving the public a car that dangerously powerful are often cited as reasons, but it might simply have been that Ford doubted that an engine so unsuited to street use could sell in such numbers.