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 unknown.
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: firstname.lastname@example.org