Harley-Davidson improved on the Panhead engine with the Shovelhead.
The Panhead and Shovelhead Harley-Davidson featured similar engines, with the major distinction being that the Shovelhead had an improved top end mounted on the Panhead crankcase. Both engines are two-cylinder, four-valve V-Twins. Harley produced the Panhead from 1948 to 1965, and the Shovelhead from 1966 to 1984. The Panhead earned its moniker for its rocker box covers that resembled inverted baking pans, and the Shovelhead for is striking coal-shovel-style covers.
Harley-Davidson replaced the Knucklehead engine V-Twin engine in 1948 with the Panhead. The Knucklehead proved to be a strong and reliable replacement for the Flathead V-Twin in 1936, but the Knucklehead was a messy engine with a reputation for oil leaks. Harley solved the problem by moving the engine’s external oil feeds inside the engine case with the Panhead. The new engine featured cubic inch displacements of 61 and 74 inches, although the motorcycle maker dropped the 61-inch version in 1953. However, the major difference between the Panhead and the Knucklehead was Harley replacing the Knucklehead’s iron cylinders with aluminum alloy to reduce weight and dissipate engine heat better. The Panhead also featured hydraulic lifters to reduce noise and downtime for maintenance. The engine had virtually the same output as the Knucklehead at 50 horsepower, which boosted to 55 horsepower in 1956.
Harley-Davidson installed the Panhead in its 1949 Hydra Glide bikes, which featured hydraulic telescopic front forks, which replaced the old-school Springer forks. The engine also powered the first Electra Glide bikes. The aluminum heads vastly improved engine cooling, which was a major problem with Knuckleheads that had a tendency to overheat at high speeds. A curious difference between the Panhead and later Shovelhead models for backyard mechanics was that the Shovelhead engine easily fit into a Panhead frame, but a Panhead engine installation required alterations to a Shovelhead frame. Panhead frames featured bowlegged tubing with a trianglular motor mount. The Shovelhead frame had different design characteristics.
The Shovelhead arrived as Harley phased out the kick-starter and introduced the electric starter. The Shovelhead had the same 74-cubic-inch, or 1,208 cc, displacement as the Panhead. Harley enlarged the Shovelhead to 82 cubic inches, or 1,340 cc in 1978 before giving way to the Evo engine in 1984. The Shovelhead essentially was an improved version of the Panhead. It featured 10 percent more power than the Panhead. Early Shovelheads kept the lower style of the Panhead engine but bolted on a new top end. The 1966 Electra Glide shed its Panhead in favor of the Shovelhead to become the first Shovelhead-powered Harley. In 1964, Harley went retro by returning the oil feeds from inside the crankcase to outside the engine, and the Shovelhead kept the design.
By adding a new top on the Shovelhead, Harley used new alloy cylinder heads with iron cylinder barrels. The motorcycle maker replaced the Panhead’s pressed steel rocker boxes with ones made of light alloy. For 1970, the Shovelhead’s bottom end from the Panhead disappeared and was replaced with a new design that included a crankshaft-mounted alternator that gave the engine a wider look. Harley also moved the external ignition points assembly inside the engine’s timing case. This required a cone-shaped cover that altered the look of the Shovelhead.