Harley-Davidson's Shovelhead engine debuted in the mid-1960s after ... as the successor to the Panhead (which itself came after the Knucklehead), it was pretty obvious that Harley-Davidson needed ...

This is a curious straddling of technologies by Harley-Davidson, especially when you consider the Flathead was discontinued one year after the Knucklehead, the younger engine, was discontinued.

Harley-Davidson isn't the oldest American marque – that distinction goes to Hendee/Indian – but it's the only one that has been in continual operation since its inception in 1903 up through ...