Nostalgic Look at Shovelhead FL Production
Remembered as the motor that powered a modern era of motorcycling.
Classic Approach
The Shovelhead is Harley-Davidson’s long-running OHV Big Twin. Some consider it a classic, while early production examples technically qualify as antiques. Yet, the Shovelhead is just as modern today as it was almost fifty-five years ago. Produced from 1966 to 1983, the engine is a contemporary icon and stands as a testament to the Motor Company's straightforward engineering approach.
Photos courtesy of Mecum Auctions.
Unofficial Moniker
The Shovelhead gets its nickname because of the shape of the rocker boxes. The engine was the third rendition of Harley-Davidson's OHV V-Twin, after the Knucklehead and the Panhead. Like its predecessors, its pseudonym was never an official moniker, but one christened by the Motor Company faithful. Unlike the Panhead, the Shovelhead's rocker arm pivots were part of the rocker boxes, eliminating the need for a cover, or pan.
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Power-Pac
First-year Shovelheads were basically carryovers from Panhead motors, but with a new top end. Its redesigned cylinder heads were aluminum versions of the Ironhead Sportster, with longer cooling fins. Dubbed the 'Power-Pac,' the lighter heads had a compression ratio of 8:1, which provided ten percent more power than the Panhead. Fed by a Linkert DC carburetor, the new Big-Twin had 74 cubic inches of displacement.
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Bottom End
The iconic motor saw numerous changes over its seventeen years of production. For the first three years, it retained the kidney-shaped timing cover from the 1958-1965 Panhead engines. Known as generator 'Shovels,' these early motors are sometimes also referred to as flat or slab side, and even 'Pan-Shovels.' From 1970 onward, Shovelheads were fitted with a new bottom end and featured a gear-driven alternator.
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Cone Motor
The change in electrical power supply gave the Shovelhead motor a new look. The alternator was located on the left-hand crankcase, concentric with the crank, in a redesigned case. Mechanical breaker points and an advance were located in the right-hand case, housed in a cone-style timing cover. Shovelheads of this era are often called 'cone motors.' The layout endured into the next generation of Evolution engines.
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Octane Chronic
Despite Harley-Davidson's financial troubles, the 1970s saw continual development of the Shovelhead motor. The 1973 fuel crisis only added to the Motor Company's woes, and challenged their decades-old reputation for producing reliable machines. Inconsistent levels of octane in gasoline led to chronic engine knock, resulting in overheating. With hotter heads, the aluminum expanded and stretched bolts, leading to gasket failure and oil leaks.
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Oil Improvements
By 1981, the Motor Company had righted its financial situation and initiated damage control on the Shovelhead. A new oil pump was fitted and the compression ratio was reduced to 7.4:1 to prevent detonation from lower-quality gasoline. The motors were also fitted with better gaskets and seals, and an 'oil control' kit was offered that included additional drain lines from the rocker boxes.
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Modern Era
The end of Shovelhead production coincided with Harley-Davidson's adoption of more modern manufacturing concepts in 1982. New methods, and no more room for development, spelled the end for the venerable Shovelhead. It was replaced with the all-aluminum Evolution engine but will endure as the motor that powered the Motor Company into the modern era of motorcycling.
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