7 Technical Facts About The Harley Davidson Shovelhead
In the year 1966, Harley Davidson launched new variants of motorcycles which had the Harley Davidson Shovelhead engines. The Harley Davidson Shovelhead had a V-twin engine which came with 74-cu.-in along with a chassis of OHV Big Twin which was considered to be one of the longest-running models in Harley Davidson. The Harley Davidson Shovelhead came up in the market in order to give more power and to add in the performance factor. This period saw the higher weights of motorcycles which came with rear-suspension, electric start options etc. The Harley Davidson Shovelhead stayed in the market from the period of 1966 to 1985.
There was a sales increase of 26 percent, which led to 36310 units. In the initial year, the Harley Davidson Shovelhead had aluminum versions of Sportster iron heads. It went on to get the name ‘Power Pac' because it was able to achieve a ten percent increase in power. This was possible with straighter ports along with long fore-and-aft fins. The valves of the Harley Davidson Shovelhead had angle drops to 78.5 degrees. The heads had lower deep combustion chambers. From the centerline, there was an intake of 40.25 degrees and in terms of exhaust, the degree range was 38.25.
The purpose of the combustion chamber kept in a shallow range is that it will finally have less surface area. This will lessen the combustion heat, which can go through the head. In comparison with the earlier versions which had the 90-degree angle for the valve chamber, the mentioned model was able to perform better when it came to the cooling factor and in the performance at the higher compression rates. The bolted-on rocker box casting saw the addition of rocker arms.
When talking about the models during the period of 1966 to 1968, the alternators were not present in it. The generators were used back then too. The models saw a four-speed gearbox which came with the all-chain drive. The Iron Sportster heads had some drawbacks like the usage of long exhaust ports. The port turns in the rear cylinders was seen to be 80 degrees in the casting and in the front cylinder, the port turns were about 107 degrees. The head turns on the casting gave various benefits like making the air go fast and can even make it to, go around corners. However, the combination of both could not be performed here.
In terms of flow value, it still had low importance when compared with the convenience, present in the carburetor along with exhaust pipe location. 1.94-inch intake and 1.75-inch exhaust was the valve sizes here. There was the talk of ‘wet sumping' in this case. There are cases where for some reason oil, which is thrown off from moving parts might get settled in the crankcase. This is not supposed to happen as it should be ideally picked up by the scavenge pump which should be returned to the oil tank. This became an issue which slowed the motorcycle down, especially when going on long rides.