The Knucklehead engine was producted with 60 cubic inches 1000 cubic centimeters desplacement, distinguished by the initials EL. From the 1941 was available also 74 cubic inches, 1200 cubic centimetres the intials were FL. It takes the name from the rocker covers shape that looks like a knuckle.
With over head valve engine Harley Davidson Motor Co. open a new era, a big aesthetics engine looks and
also gain more reliability and power from the Flathead engine.
Introduced in the 1936 it was producted untill the 1947, 24340 units with 60ci engine and from 1941 to the 1947 with 74ci 15845 units for a total of 40185 motorcycles producted.
The Panhead engine, distinguished by the letters EL 60ci 1000cc and FL 74ci 1200cc, takes the name from the form of the valve covers that loks like a pan. Similar for teachnical features to the predecessor Knucklehead engine.
The big difference between the two engines come from the introduction of self-adjusting
hydraulic lifters, installed on the top of the valve pushrods.
It was producted 14015 unitis from 1948 to the 1952 with 60 ci engine and 116798 units from 1948 to 1966 with 74 ci engine, for a total of 130812 engines.
Panshovel engine, also known as Earlyshovel, 74ci 1200cc, keep the big block crankcase shape, allow the placement the electricity generator just under the front cylinder and the ignition distributor just between the front cylinder valve block and the alternator.
Heads are the big different from Panhead engine, now rocker arms are located on the valve covers that look like a shovel. Other changes are the shorter V shape intake manifold and rocker arms lubrification system.
Producted from 1967 to 1969 for a total production of 22122 units.