5 Facts About The Harley Davidson Panhead
The year of 1947 saw two versions of the Harley Davidson Panhead where one was the 61-inch version and the other was the 74-inch version. The Harley Davidson Panhead with the V-twin engine has evolved with time, in terms of engine built and the chassis. In the fall of 1947, the Harley Davidson Panhead with the two announced versions were supposed to hit the market by the following year. This was originally to replace the Knucklehead version. The 61 version had a bore and stroke of 3.3125 along with 3.5 inches. The 74 version had the bore and stroke of 3.4375 along with 3.96875. The final horsepower was claimed to be around 55.
The following Harley Davidson Panhead models were able to successfully overcome the heating problems which were prevalent in the 74 and 80inch models. In terms of the engine when it came to the Harley Davidson Panhead it seemed to have used the former bottom end. In order to help with the new engine to match up the heat of a higher-power operation, the head cooling was boosted to a great extent. This was done by switching the material used form cast-iron to that of aluminum. This is because the aluminum has three times conductivity when compared with the iron.
The Harley Davidson Panhead had its valves placed on shrunk-in hard seat rings. This was because even the aluminum which is of high strength is not that strong to take the position of valve seating. Since the aluminum heads were known to expand with the increase in heat to a greater extent, the decision of placing hydraulic clearance adjusters in the top of the pushrods which were four in number here was made. The ultimate aim for this decision was to clear out the necessity for traditional manual adjustment in regards to eh valve clearances.
However, this came up with the clause where it kind of blocked ports in hydraulic adjusters. This led to the collapse and sometimes in creating valve noise. Cast-iron was made as a choice for the cylinders then. The aluminum heads, which were taken newly were cast from the high-hot-strength alloys. These alloys were the same which was used in the engines which were used in the B-17, F4F Hellcat combat aircraft and in P-47. In order to simplify the issues there was the thought of putting the pans which gave the name for the engine. The one-piece valve covered these pans which, however, failed to solve the issue with oil containment completely.
The Harley Davidson Panhead still had the issue of oil leakage which happened in the top end. To solve the issue of valve noise and to tone it down, a felt blanket was kept in the top part of the rocker gear. This also paved way for an alternate source of oil. The designs of the rocker arms were changed. Initially, it seemed to rotate on stationary shafts. But in the latter part, they were bolted together as trunnions. There was an oil pressure loss at times when the end plugs came out which was caused by the hollow rockers.
