In fact, the manufacturer had an entire line of head-themed engines, including the Knucklehead, Panhead, and Shovelhead, with some featuring in the rarest Harley-Davidson motorcycles ever built.
Harley-Davidson Big-Twin engines have always tended toward the upper end of their contemporary displacement ranges, which builds up steadily over time. Case in point, the 1,200 cc Shovelhead was ...