The engine gained the nickname “Shovelhead” because its rocker covers look a little bit like an upside-down coal shovel. While the engine did have problems, it gave Harley-Davidson a 26% sales increase during the early part of its timeline.
The engine earned the nickname "Shovelhead" due to its rocker covers resembling an upside-down coal shovel.  Despite having issues, it led to a 26% rise in Harley-Davidson's sales during its initial period of operation.