Harley Shovelhead: The Infamous Yet In Demand Engine

The Harley Shovelhead engine made its debut in 1966. Taking its name from the rocker covers looking like a coal shovel flipped upside down, the Shovelhead succeeded the iconic Panhead engine and was ultimately the last of the FL series engines.

Although plagued with problems, its distinctive look and improved power output meant Harley sales got a much needed 26% increase.

Production of the Shovelhead ran from 1966 to 1984, and during this time, the engine underwent several upgrades. These improvements ranged from increased cubic inches to the addition of electronic ignition systems. Harley-Davidson focused on innovation, continued to refine the engine while retaining the classic design and sound riders loved.

The Shovelhead held a prominent place in Harley-Davidson’s lineup for nearly two decades. It was the engine that bridged the gap between the Panhead and Evolution engines.

Today, the Shovelhead has a strong following with several owner and fan clubs but the general consensus among the majority of Harley fans was that the engine and several of the motorcycles it was used in lacked the quality the company had previously been known for.

The Shovelhead engine’s cause isn’t helped as it coincided with the AMF takeover. The AMF Harley era ran from 1969 to 1981 – 3 years after the Shovelhead release and ended 3 years before its replacement.

History and Evolution

1978 Harley Shovelhead with the new larger 80 cubic inch (1340cc)

Knucklehead and Panhead Era

Harley Davidson introduced the Knucklehead engine in 1936, marking the beginning of an important era in the company’s history. This overhead valve V-twin engine featured distinctive rocker covers, which resembled knuckles, giving it its name. The Knucklehead was succeeded by the Panhead engine in 1948, marked by improved oil circulation and hydraulic valve lifters.

Shovelhead Era

Harley Davidson launched the Shovelhead engine in 1966, as a redesign of its predecessor. During this era of the company’s history, Harley Davidson underwent significant changes in ownership, including a merger with American Machine and Foundry (AMF) in 1969.

Evo Engine

The Shovelhead engine was replaced by the Evolution engine in 1984. This new engine featured an aluminum block and cylinder heads, as well as a higher compression ratio. Harley Davidson’s motorcycles finally began to regain their reputation for reliability and performance with the introduction of the Evo engine.

Twin Cam

In 1999, Harley Davidson introduced the Twin Cam engine, which replaced the single camshaft of engines. This offered improved power, torque, and a smoother ride.

The Twin Cam engine has since undergone several updates, including the Twin Cam 88, Twin Cam 96, and Twin Cam 103.

Knucklehead: Overhead valve V-twin, distinct rocker covers
Panhead: Improved oiling, hydraulic valve lifters
Shovelhead: Redesigned Panhead, old coal shovel shaped rocker covers
Evolution: Aluminum heads and cylinder for higher compression ratio
Twin Cam: Two separate camshafts, improved power, and torque

Shovelhead Engine Specifications and Performance

Engine Displacement

The Harley-Davidson Shovelhead engine is a member of the Big Twin family, featuring a displacement of 74 cubic inches (1200cc) in its original version. In 1978, Harley-Davidson introduced an 80 cubic inch (1340cc) variant to increase performance capabilities.

Combustion Chamber

The Shovelhead’s combustion chamber design was an evolution from the preceding Panhead engine. Its chamber shape is more squared-off, providing a better air-fuel mixture burn, resulting in more efficient power generation and improved overall performance.

Horsepower

The horsepower output of the Shovelhead differed across the years and models. Early versions, such as the 1966 FLH, produced 60 horsepower, while later versions, like the 1984 FXWG, generated up to 65 horsepower. Performance improvements were made possible by continuous engine refinements throughout its 18-year production run.

Compression Ratio

The Shovelhead engine typically had a compression ratio of around 8:1. However, this ratio varied slightly with different models and throughout the years. While the compression ratio remained largely unchanged, advancements in engine design allowed the Shovelhead to maintain its status as a reliable and strong-performing motorcycle engine.

Models and Variants

FLH Models

The Harley-Davidson Shovelhead FLH models were touring bikes with a focus on comfort and long-distance riding. These bikes featured a large front fork, windshield, and saddlebags, making them ideal for cross-country trips. Some notable FLH models include the FLH Electra Glide and the FLH Police Special.

FX Super Glide

The FX Super Glide was introduced in 1971 as a combination of the FLH frame and the XLH Sportster forks and boat-tail fender. Different variations of the FX Super Glide were available, including the FXE and FXS models.

Low Rider

Harley’s Shovelhead Low Rider, introduced in 1977, was designed to cater to riders seeking a lower seat height and improved handling. The Low Rider featured a unique seat design, longer rear shocks, and the iconic “Mag” wheels, adding to its stylish appeal.

Sturgis

The Sturgis model, named after the famous motorcycle rally in South Dakota, was introduced in 1980. It featured a blacked-out engine, cases, and exhaust, with distinctive orange accents. The Sturgis was a well-regarded motorcycle that was designed to appeal to riders based on its aesthetics and how it made them feel while riding, rather than just its functionality.

FLT

Introduced in 1980, the FLT was a touring-oriented bike designed for comfort on long rides. It featured a redesigned frame with a rubber-mounted engine, reducing vibrations and providing a smoother ride. The FLT also introduced the five-speed transmission, improving overall performance and fuel efficiency.

Rubber-Mounted Models

Rubber-mounted Shovelhead models, such as the FLT and FXR, were designed to address concerns about excessive vibration in earlier models. By isolating the engine with rubber mounts, these bikes offered improved handling, ride quality, and rider comfort, making them a popular choice among Harley enthusiasts.

Technical Features

Cooling and Overheating

Shovelhead engines, being air-cooled, can face cooling challenges. Overheating can result in engine knock, damaging the motor. To manage this, proper maintenance and oil selection are essential.

Alternator and Electric Starter

The Shovelhead introduced an alternator, improving the electrical system compared to its predecessor. It also featured an electric starter, offering easier and more reliable starting and eliminating the need for a kickstart.

Belt Drive and Chain Drives

Shovelhead models initially used a primary chain drive, ensuring efficient power transmission. In later years, some models switched to a belt drive, offering lower maintenance and quieter operation.

Common Issues With The Harley Shovelhead

Oil Leakage

Another common issue with Harley Davidson Shovelhead motorcycles is oil leakage. This can often be traced back to a worn-out or damaged gasket. Replacing the gasket, particularly on the rocker box and primary cover, can help resolve this problem.

Another cause of oil leakage is a cracked oil line. Inspecting the oil lines and replacing them as needed can prevent further leakage. Maintaining proper oil levels and using high-quality oil can also help mitigate this issue.

Engine Knock

The dreaded engine knocking was always a concern for Shovelhead owners. This issue could be caused by incorrect ignition timing or worn-out components but more likely it was the poor quality fuel available at the time rather than a design fault.

To resolve the problem, checking and adjusting the ignition timing, using higher octane fuel, or replacing worn parts may be necessary.

In some cases, excessive carbon buildup in the cylinder can lead to engine knocking. Using a fuel additive to remove the carbon buildup or having the combustion chamber professionally cleaned will help address this issue.

Overheating

Overheating is another common problem with Shovelhead motorcycles. This can often result from inadequate oil circulation. Another cause was that for some unknown reason the cylinder heads only had 10 cooling fins which caused overheating sometimes leading to blown gaskets and even damaged head bolts.

Ensuring the oil pump is functioning properly and maintaining correct oil levels can help prevent overheating. Additionally, installing an oil cooler or upgrading to a more efficient cooling system can help reduce the risk of overheating.

End of the AMF Era

AMF Harley — After 12 years AMF finally concluded creating motorcycles wasn’t as easy as bowling equipment and sold HD.

During the 1970’s AMF went into decline and in 1981 they sold Harley-Davidson for $80 million to a group of investors lead by Vaughn Beals and included Willie G Davidson, the Grandson of William Davidson, the original company co-founder.

Willie G and his partners instantly made improvements to the Shovelhead engine with a new oil pump being top of the list. They also improved valve guides and lowered the compression so that the engine could run on the poor quality gas available at the time in America due to the mid 70’s oil embargo.

Customization

Shovelhead motorcycles are a popular choice for customization due to their classic design. Shovelhead Choppers are common among enthusiasts, as they lend themselves well to personal expression and modification.

The sky really is the limit with what Shovelhead enthusiasts can achieve with their creativity and skill. With a rich history and dedicated following, the Harley Davidson Shovelhead remains a favorite platform for those who wish to make their mark in the world of customized motorcycles.

Resources and Forums

Today, Shovelhead bikes are in demand. Some are looking for a donor bike for a custom build, others are wanting to take their first steps into owning a vintage Harley and others are just looking to relive their youth by purchasing the motorcycle that first got them on 2 wheels.

Whatever the reason, when looking to buy Shovelhead engines and motorcycles, there are a variety of resources available online.

When looking to buy I recommend the Chopper Exchange as a good starting point. Whichever Harley you’re looking for they always have a good selection so you get a good idea of the prices they are going for.

Forums such as the Harley Shovelhead owners group on FB are dedicated platforms for owners and enthusiasts. These groups provide a space to connect with other Shovelhead owners, ask questions, and share experiences related to maintenance, upgrades, and riding experiences.

FAQ

Why are the AMF Harley years considered the worst era of Harley Davidson history?

The AMF (American Machine and Foundry) years are often considered the worst era of Harley-Davidson history because of a number of factors. From 1969 to 1981 Harley-Davidson was owned by AMF, a company that had no experience in the motorcycle industry.
AMF’s focus was on profitability, which led to declining quality control and a decrease in the overall quality of Harley-Davidson motorcycles.
Additionally, during this time, Harley-Davidson faced increased competition from Japanese motorcycle manufacturers, who were producing high-quality, reliable bikes at a lower cost. Harley-Davidson struggled to keep up with this competition and was losing market share.
The AMF years were also marked by labor disputes and strikes, which further impacted the company’s ability to produce high-quality motorcycles.
All of these factors combined to create a negative reputation for Harley-Davidson during the AMF years, and it took the company many years to recover and regain its reputation as a high-quality, American-made motorcycle brand.

Where do Harley Shovelheads rank in the company’s other overhead valve V-twin engines?

Although sales jumped by 26% on the release of the Shovelhead engine, it was plagued by mechanical problems from the start. For some Harley aficionados, the Shovelhead is considered the worst engine Harley ever built. It doesn’t help it coincided with the AMF Harley era either.