American Icon: Restored 1938 EL Knucklehead
Oil leaks meant the Knucklehead was not heavily promoted for its first two years of production.
Venetian Blue
The Harley-Davidson EL Knucklehead set a standard in motorcycle design that has transcended time. Introduced in 1936, the EL could be described as sublime — something of such excellence or beauty as to inspire awe. With enough good looks to make any Harley-Davidson aficionado weak-kneed, this restored 1938 Venetian Blue EL goes far to satisfy that definition — it is also up for sale.
Sport Solo
On the block in January 2020, the EL is expected to fetch upwards of $50,000 at Mecum's annual motorcycle auction held in Las Vegas, Nevada. The Special Sport Solo pictured here was listed at $435 in 1938. For an additional $49.75, the Deluxe Solo Group could be added, which included items such as a taillight, jiffy stand, saddlebags and more importantly, chrome.
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American Icon
First introduced in 1936, the 61 cubic-inch motor was Harley-Davidson’s first overhead-valve Big Twin. The EL Knucklehead started a culture of motorcycling and has since become an American icon — one that still defines Harley-Davidson. Development of the Knucklehead began in 1931, but Motor Company engineers had previous experience with OHV engines dating back to the eight-valve Peashooter single racer.
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Improved Design
Cradled in a twin down-tube frame, the Knucklehead produced around 36 horsepower with 6.0:1 compression. A four-speed constant-mesh transmission with a multi-plate clutch was a vast improvement over previous designs. The EL weighed in at 565 pounds wet with one gallon of oil. Despite objections about a severe oil leak from the rocker boxes, the EL was released in June of 1936.
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Knucklehead Woes
Much of the reason for chronic rocker box leakage was the complex shape that required sealing. When heads heat up and cool down, gaskets are subjected to expansion and contraction — it is still a major concern even by contemporary standards. Adding to the Knucklehead's woes, the initial production run was also prone to valve spring breakage from poor rocker arm lubrication.
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Increased Durability
Harley-Davidson's iconic new motor was not heavily promoted for the first two years of its production. By 1937, valve spring metallurgy was improved and repair kits were issued to dealers for the approximately 1900 affected bikes. For increased durability, the engine was again modified in 1938, by enclosing the valve springs and stems. The common practice at the time was to have the valve stems and springs exposed for better cooling.
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Performance Credentials
With the improvements in place, Harley-Davidson set about establishing the EL's performance credentials. Motor Company engineer Joe Petrali builds a Knucklehead-powered streamliner and sets a new land speed record of 136.183 mph in 1937. Pasadena Motorcycle Police officer Fred Ham sets a 24-hour high-speed record run at Muroc Dry Lake, California by riding 1,825 miles at an average of 76.02 mph — only stopping for fuel, oil, and fruit juice.
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Affordable Knucklehead
The EL Knucklehead was produced until 1947 when it was replaced by the Panhead. Tinged with irony, the iconic design's demise came about as a result of a prosperous post-war American economy and reduced tariffs on aluminum. Recently, the original condition Knuckleheads have sold for upwards of $100,000. Adjusted for inflation, a $485 1938 EL would cost an affordable $8500 in today's money.
>>Join the conversation about this classic Knucklehead right here in the Harley-Davidson Forum!
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