![]() ![]() The larger compression ratio on the newer engines was still a serious problem, due to the low fuel quality and octane. Many owners would swap the units for an older point-ignition system for reliability. Valves and guides were prone to problems, along with more overheating, detonation, and oil consumption.Īnother problem that arose in 1979 was that the motors were fitted with electronic ignition units, which were prone to failure. However, the changes were not enough for the declining quality of American fuel at the time. After realizing they would need some serious improvement to fix their current situation, they produced some updates in 1978 to the engine that consisted of a larger displacement, and steel struts cast into the pistons to prevent them from expanding from the heat. AMF tried to combat this by producing more units in 1976 despite the engine's problems, which ended up leading to a damaged employee reputation, along with seriously declined quality in their units. Engine knock became a large problem causing overheating that led to blown gaskets and damaged head bolts. With the United States involved in the 1973 oil crisis, gasoline had a much lower octane and consistency that severely hurt the engine's performance. However, in 1974, the engine started to show many more problems. The carburetors were changed to Zenith-Bendix, improving flow and power that started to gain a better image for the engine. In 1970, the alternator was redesigned for less strain, hidden behind a new and redesigned side case. After AMF took control, the merged company started to make attempts at improving the engine with their own funds. Īs a way to try to combat their financial struggles, the company merged with the American Machine and Foundry (known as AMF) hoping to gain help from their struggles. With Harley-Davidson trying to fix the engine rather than research and develop, they fell far behind the competition of the cheaper and more reliable Japanese bikes taking control over the market. Numerous Harley technicians even stated that without necessary top-end modifications, the motors would often last only between 500 and 5,000 miles. With a lack of oil and excessive heat, the valves were prone to sticking and destroying the top end. The excessive overheating in the motors also caused serious problems, which frequently led to failure. Oil leakage and consumption became such a problem with the bikes, many owners reported losing as much as a quart of oil every 500 miles. ![]() Another problem was that oil would pool in the crankcase rather than being pumped, causing the engine to overheat and seriously harm performance. Another problem was that oil would pool in the cylinder heads, causing it to leak into the valves and burn oil. The engines had only 10 fins for cooling, which caused them to run hot. Throughout the Shovelhead's run, the engine had many different changes made to it to improve power, cooling and oil consumption. The Shovelhead engine was created as the previous Panhead engine was becoming obsolete, with many Harley-Davidson owners demanding more power to compete with the more modern motorcycles. Early Harley-Davidson Shovelhead engine on a motorcycle frame History While the engine did have problems, it gave Harley-Davidson a 26% sales increase during the early part of its timeline. The engine gained the nickname “Shovelhead” because its rocker covers look a little bit like an upside-down coal shovel. This gave the new engine an extra 10 horsepower, along with a different appearance. When the engine was first produced, the Shovelhead had a shallower combustion chamber, larger valve drop for both intake and exhaust, better porting, and stronger valves and pistons. Models 1975 and later use Dot 5 brake fluid.The Shovelhead engine is a motorcycle engine that was produced by Harley-Davidson from 1966 to 1984, built as a successor to the previous Panhead engine. Shovelhead models from 1966 to 1975 use Dot 3 brake fluid. HD Primary Chaincase is used in the primary chaincase. All shovelhead models 1970 and later use HD Type B fork oil. HD Hydra-Glide fork oil is for 1966 to 1969 models. Harley-Davidson makes two types of fork oil for shovelheads. The transmission uses 1.5 pints of HD transmission lubricant, although many people use 75w90 gear oil mixed 3-to-1 with Lucas oil. Harley-Davidson recommends 4 quarts of SAE 50 or 60 engine oil in all 1966 through 1984 shovelheads. The primary lubricant should be changed at 5,000-mile intervals, the transmission oil every 10,000 miles and the the fork oil every 20,000 miles. The official maintenance recommendation is to change engine oil every 5,000 miles, but changing the oil at 2,500 miles is a good idea for an older shovelhead. That keeps the engine and other moving components lubricated and operating efficiently. Motorcycles need their main fluids changed at regular intervals. ![]()
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