A new Harley Davidson big twin engine is always a momentous occasion but the replacement for the Panhead, the Shovelhead, turned out to be the worst engine Harley ever built and, combined with the dark days of the AMF custodianship of the company, marked a difficult period that Harley was lucky to survive.
Harley Davidson doesn’t do things in a hurry. Prior to the 1966 Shovelhead engine, there had been only three big twin engine designs: the Flathead, Knucklehead, and Panhead.
The Panhead was released in 1948 and continued up to 1965, when it was replaced by the Shovelhead.
In case you are ignorant of the reasons for Harley Davidson engine names, it’s quite simple. The Flathead was just that: a sidevalve engine that required a simple flat ‘lid’ for the cylinder. The Knucklehead was the first overhead valve design and the name derives from the shape of the rocker boxes on the cylinder heads, which resemble knuckles on a clenched fist.
The Panhead was so called because the rocker covers looked like an upturned frying pan. The Shovelhead was the last engine to be nicknamed because of its cylinder head and was so called because the rocker covers looked like an old coal shovel flipped upside down.
By the early 1960s, the Panhead was becoming obsolete and simply not powerful enough to compete with more modern motorcycles coming out of Europe.
For the Shovelhead engine, Harley Davidson was looking for more power and improved reliability. It featured a shallower combustion chamber, increased valve lift, improved porting, and stronger valves and pistons. All this gave the engine an extra 10 horsepower and a different look.
The engine had big problems right from the outset, some terminal, although eventually, Harley enjoyed a 26-percent sales increase thanks to the new engine.
The design of the Shovelhead was flawed from the start. The barrels had only ten cooling fins which weren’t sufficient and the engine ran hot. Smoky engines were common as oil would pool in the cylinder heads and leak down the valve guides to be burnt in the combustion chamber. Similarly, oil would pool in the crankcase, causing further overheating along with a loss in power. Some owners reported using a quart of oil every 500 miles!
The excessive heat would cause the valves to stick open, causing untold horrors in both the head and piston as the valves and pistons touched. Even Harley Davidson technicians warned that without proper modifications to the cylinder head, engines might only last between a few hundred and a few thousand miles.
All this was bad news for Harley as it spent more time trying to fix the problems than it did on research and development, causing it to fall further behind the competition, which by now included the ever-growing Japanese threat.
Harley was struggling financially, not solely because of the Shovelhead engine, although the problems in that direction did not help as the company’s reputation suffered because of the reliability issues.
In 1969, American Machine and Foundry (AMF) bought a controlling stake in Harley Davidson and tried to turn the company around by slashing the workforce and cost-cutting in the production processes.
It was all disastrous: the remaining workforce went on strike and product quality slumped. AMF simply didn’t understand how to market motorcycles to enthusiasts.
However, the merger did at least release funds to continue the development of the Shovelhead engine. Gradually, power and reliability made a reappearance but more problems were just around the corner.
In 1973, the first oil crisis hit the U.S. The members of the organization of Arab Petroleum Exporting Countries (OAPEC), led by Saudi Arabia, proclaimed an oil embargo. The embargo was targeted at nations that had supported Israel during the Yom Kippur War.
The octane rating of gasoline was reduced to try and stretch supplies but this had a disastrous effect on the Shovelhead engine. Engine knock became pronounced, causing overheating and leading to blown gaskets and damaged cylinder heads.
Incredibly, AMF’s solution to the problem was to build more engines without solving the problems, leading to further reputation damage as quality declined.
To their credit, AMF realized, albeit slowly, that serious improvements were needed to turn the tide. Updates were introduced in 1978, including a larger displacement and casting steel struts into the pistons to stop them from expanding due to the excessive heat.
But none of this addressed the real problem, which was the quality of the gasoline, which was getting worse, not better. The old problem areas of valves, guides, overheating, knocking, and heavy oil thirst remained in the engine and AMF seemed incapable of sorting them out.
The tale of woe for the Shovelhead just doesn’t seem to have an end. In 1979, electronic ignition was adopted but, typically, they were prone to failure so owners replaced the units with old-style points ignition.
Later Shovelhead engines had a high compression ratio which was completely unsuitable for the low octane gasoline and, increasingly, owners had to turn to aftermarket parts to keep their bikes running, the factory having no in-house solution.
In 1981, a consortium of investors, including Willie G Davidson, bought back AMF’s share of the company for $80 million. This was the best thing that could have happened to the company and work started immediately on not only trying to sort out the Shovelhead’s problems but also working on a long-overdue replacement engine, which would appear in 1984. Called the Evolution and featuring aluminum cylinder barrels and heads, it marked the turnaround in fortunes for the company that everyone, from employees to customers, had been waiting for.
The motorcycles that had the Shovelhead engine fitted are some of the least fondly remembered of any in Harley Davidson’s history. With no alternative engine, the Shovelhead was fitted to all of the company’s Big Twin models, even though the engine’s weight caused steering and handling problems, not helped by the rudimentary suspension of the time. The styling of some of the models was questionable.
Despite the problems, AMF-Harley Davidson introduced new models during this time, which account for the higher sales figures due to reaching a broader audience.
Today, the bad old days of the AMF/Shovelhead years are an unfortunate footnote in the history of the company which happily prospered under its new management. It could all have been so very different.
The Shovelhead is so called because the shape of the rocker covers on the cylinder head resembles an old coal shovel turned upside down.
Shovelhead models sell for anything from a couple of thousand dollars up to $10,000+
The Shovelhead engine was replaced by the Evolution engine in 1984.