The incredibly successful Panhead engine was introduced by Harley-Davidson in 1948, the same year they produced their last big twin side-valve engine. The new powerplant was an instant success and in continuous production for the next 17 years with approximately 120,000 Panhead motorcycles rolling off the production line between 1948 and 1964.

The most obvious difference between the new Panhead and the Knucklehead engines was the use of cast aluminium cylinder heads with integral bronze valve seats and re-designed cylinders for greater strength.

All Panheads were equipped with hydraulic tappets from day one, however, the initial setup incorporated the hydraulic unit into the pushrods. This was revised in 1953 with a new oiling system which included a serviceable filter screen and the removable hydraulic tappet positioned directly in the cam-follower. These lifters worked well but were often unnecessarily

replaced with solid lifters, whereas poor