Hercules Engine News

Unraveling Production Dates


| August/September 2002



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There are many mysteries surrounding the production of Hercules-built engines. Slowly, some of these mysteries are being unraveled.

Several years ago a chart was developed to aid in determining when a particular engine was most likely built. Many of you are probably familiar with that chart, but arriving at an exact date is very elusive even if you have the original records.

First, there is the production of the various parts that make up a complete engine, the production of which could easily be spread over several months. Beginning in late 1924, many engines had one or more parts with casting dates on them. Often times the casting date order does not follow the serial number order very well.

Second, several months could pass before all the parts were finally assembled into a complete engine. From there, the engine was tested, painted and, finally, a serial number tag was applied from a supply that had already been numbered.

Third, the engines were then shipped by rail to warehouses, dealers or individual purchasers. And even though a certificate was issued to the eventual owner, it could be dated quite sometime after the engine was actually built.

To complicate the dating issue a little more, series of tags from a supply already numbered were stamped up for each sized engine group listing the horsepower, model and rpm. With data from nearly 4,000 of these engines now on hand, these blocks of serial numbers become evident when all known numbers are listed chronologically. Table 1, taken from a segment of the list of currently known engines, is a good illustration of this.