Hercules Engine News

By Staff
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The spark plug on Jeff Leggett's 2 HP ARCO
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Serial no. 314192, is set in the cylinder head instead of in the cylinder on the ignition side, as normally found.
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The gas engine hobby is always full of surprises. Take, for
instance, the Hercules-built ARCO brand of engines, which have
always had an ‘air of mystery’ about them. The ARCO-branded
engines were used on orchard sprayers built by the Hardie
Manufacturing Co. of Hudson, Mich., from 1920 through 1928. Hardie
used other engine brands before and after these dates.

The ARCO was likely the first Hercules-built engine to use the
ubiquitous Wico magneto. Evidence indicates that the Wico PR was
introduced before the more common Wico EK.

Available evidence suggests a round, Hercules-sized decal was
stamped on the hopper side or sides of at least a few ARCO engines.
We know that the oval ARCO decal was normally applied at the
Hercules factory, because pictures exist of ARCO-decaled engines
sitting among other Hercules-brand engines at the Hercules factory.
There have also been some discrepancies in the color shade.
I’ve owned two ARCO originals, and their colors were a subdued
blue with a slight gray cast to it. Other owners have reported more
grayish and even green colors.

From data I’ve gathered, fuel mixer types used on ARCO
engines are evenly split. About half have the common cast iron
Hercules J-type mixer, and the other half have the 3/4-inch
Lunkenheimer mixer. The use of the Lunkenheimer mixer is
understandable, as it could better handle the fuel supply when the
sprayer was operated on an uneven surface. Whether the Lunkenheimer
was assembled on the engines at the Hercules factory or added later
at the Hardie  factory to meet customer demands is

A further mystery has arisen from a photo that Jeff Leggett sent
of his 2 HP ARCO GH. Surprise! Jeff’s ARCO has the spark plug
in the head, just like the Jaeger engine we discussed in the
November 2003 issue of GEM. Did Hercules offer this
special head to the Hardie Co.? If so, what was the reason behind
it? Was it because the Jaeger-style head was available and
Hercules’ normal supply was exhausted? Or did someone simply
mix and match ARCO and Jaeger parts when making one engine out of
two older ones?

So far, this is the only ARCO engine found like this. Its serial
no. is 314192, which places it being built in the last half of
1924. The Jaegers that have their spark plug in the head were built
in late 1923 or early 1924. That fact alone may raise many more
questions than answers to this interesting mystery, and it proves
that the gas engine hobby is always full of surprises.

Glenn Karch is a noted authority on Hercules engines.
Contact him at: 20601 Old State Road, Haubstadt, IN 47639, or
e-mail at: glenn.karch@gte.net

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