Carl's Cycle Supply 1937 Knucklehead Story

Harley-Davidson pulled ahead of Indian in 1936 with the introduction of its first overhead valve V-Twin. Now nicknamed the “Knucklehead” for its bulbous rocker boxes, surprisingly the new Harley-Davidson big twin was developed in Depression era America. The frame, forks, engine and much of the styling were all new. And while Harley-Davidson had built OHV racing engines for a couple of decades and even OHV singles for mass production, this was their first production overhead valve V-Twin.

Interestingly, Knucklehead experts speak of three different engine versions in the 1936 model year. Minor problems were attended to as running changes and production continued. The first engines built had problems with valve spring breakage, poor rocker arm lubrication and leakage of oil from the top end. Spring metallurgy was improved, rockers redesigned, and repair kits were sent out to dealers to fix the over 1000 affected new bikes already on the road. Many changes were made through the end of production in 1946, but most agree the prettiest bikes are the pre-War machines like this week’s subject.

Styling at Indian and Harley-Davidson reached a new height in this era. Harley’s Art Deco “Comet” tank emblem was used from 1936 to 1939. With new oval section springer fork tubes, a more graceful muffler and the tank mounted speedometer, the new Harley was probably the most stylish American motorcycle to date. For 1936 the EL could be bought in several two-tone paint jobs including Sherwood Green with Silver, Teak Red with Black, Venetian Blue with Croydon Cream, Nile Green with Maroon plus Dusk Gray with Royal Buff, this bike’s colors. A few technical problems plagued first year machines, but America was coming back economically and timing was perfect with over 1500 first year sales.

Highly prized by collectors, the 61 and 74 cubic inch OHV twins were made for 12 model years, 1936 through 1947. The valve train became enclosed in 1948 and the moniker “Panhead” was applied. In 1949 the hydraulic fork Duo-Glide was released and Harley-Davidson Big Twin styling was set for over half a century to come.

This fine 1937 EL is on loan from Robert Hyler of Illinois and just arrived for display at the National Motorcycle Museum. It is one of about a dozen Knuckleheads on display including those belonging to musician and music producer Dan Auerbach.

Specifications:

Engine: Overhead Valve, 45 Degree V-Twin
Bore & Stroke: 3.31″ x 3.50”
Displacement: 61 Cubic Inches/ 988 cc’s
Compression Ratio: 7: 1
Horsepower: 40HP
Carburetion: 1.25 Inch Linkert
Primary: Duplex Chain
Transmission: 4-Speed, Hand Shift/Foot Clutch
Final Drive: Chain
Brakes: Drum, Front & Rear
Electrics: 6 Volt Battery, Coil & Points
Frame: Steel / Double Down Tubes
Fork: Springer / Oval Tubing
Rear: Rigid, Sprung Seat
Wheels / Tires: 4.50″ x 18″
Wheelbase: 59.5 Inches
Weight: 565 Pounds
Top Speed: 95mph