Harley-Davidson Shovelhead engine
The Shovelhead is an air-cooled, 45 degree, V-twin motorcycle engine manufactured from 1966 to 1985 by Harley-Davidson. Initial models had an engine displacement of 1,208 cc (74 cu in). Roughly halfway through production of the 1978 model year, this was increased to 1,340 cc (82 cu in) for some of Harley's Big Twin bikes.[1] 1340cc, referred to by the company as 80ci., engines were optional on FLH models halfway through 1978 and through all of '79 before becoming standard equipment for FLH models in 1980. These bikes were referred to as FLH-80 Electra Glide II models. FX model bikes continued to be offered with either 1200 or 1340 cc engines till 1981 when 1340cc, also referred to as 80 ci., was made standard across the Big Twin line.
The "shovel" cylinder head represented an offshoot of the Harley-Davidson Knucklehead engine but featured a slightly different look. The name was derived from the appearance of the rocker box covers. Because these covers bring to mind the head of coal shovels when inverted, the name shovelhead was a natural progression. The shovel engines powered Harleys up until the introduction of the Evolution engine in 1984, ending the reign of the "shovel" as enthusiasts frequently call these engines. The shovel engine does not have covers, per se, but rocker boxes and rocker arms which pivot on shafts. The design provided more than a unique look; it produced 10% more horsepower than the panhead engine which it replaced. From 1966 through 1969 the shovelhead kept the panhead style lower end. These early style shovelheads with the generator bottoms were often referred to as slabside shovels. From 1970 on the shovelheads used an alternator bottom often termed a cone shovel.
A number of third-party engine manufacturers produce custom Shovelhead-style engines, in a variety of bores, many much larger than the original design displacements. Each manufacturer includes upgrades to the original design to improve the performance and reliability while still providing the original styling and overall engine structure.