20601 Old State Road Haubstadt, Indiana 47639
When Hercules Gas Engine-Company began producing model D engines
in January 1914, their design was not brand new and unique. The
engines had the general appearance and many features to be found on
the model CX engines produced at Sparta, Michigan, in late 1912 and
The 11/2, 4, 6, 8, and 10 HP size
Hercules-built model D engines retained the same physical
dimensions as those built at Sparta. The general appearance was
also much the same. The primary differences on the four larger
sizes was a change in the water hopper, a change in the fuel mixer
and fuel tank spout, and a slight change to the rear of the
cylinder. There was also a governor modification with the addition
of a speed control screw. The decal was changed and the hopper tag
The 11/2 HP size was changed even less.
Essentially, the only changes were the fuel mixer, the fuel spout,
the hopper tag and the decal. The same block, head and other
operating parts, with a few modifications, were used on the
Hercules engines until 1929.
It would be later in 1914 before the Hercules-built engines
would have a tag. It was first located on the engine base below the
igniter before being moved to the top of the water hopper. Serial
numbers began at 50,000. The model D engines had no tag.
For those hunting parts, the Economy model CX engines built at
Sparta and the subsequent engines built at Evansville have a great
deal of parts interchangeability.
Interestingly, the 2 HP Sparta Economy was never redesigned and
remained as the model CA. Evansville production began with
newly-designed 21/2 and 23/4 HP engines.
These illustrations, taken from catalogs, show the 1 HP Sparta
Economy and an example typical of the 4, 6, 8, and 10 HP sizes.
Without any physical changes, Hercules related these engines to
11/2, 5, 7, 9, and 12 HP by mid-1914.