Hercules Fuel Systems

Reprinted from the August 1995 issue of the
Gas Engine Magazine

Hercules Engine News
Including Economy, Arco,
Jaeger & Thermoil

by Glenn Karch
Old State Road
Haubstadt, Indiana 47639 .

     The fuel system on Hercules built hit and miss engines is rather simple, but a few comments are in order.  nowadays many original engines have rusted or gummy fuel tanks.  Starting off with a new fuel tank is likely the best option rather than patching, using sloshing material or using solvents to remove gum.  Ready-made new tanks up to the 7-8 HP size are available from several suppliers.  Be sure that the replacement tank has a vent on the top; otherwise, gas will bubble out when filling the tank.
     Tanks were held in the engine base with a combination of wires and rods, although the design changed somewhat between the older and new models.  If the fuel spout is missing, replacements are available on the used parts market, and new ones with the flip top lid are available from some suppliers for the 1 1/2 - 2 HP size engines.  
     For more trouble free operation, the fuel supply pipe should have a fine mesh bras screen soldered into the end of the pipe to keep out dirt particles that may be in the fuel tank.
     Check valve sticking is becoming more of a problem.  Apparently, modern day gasoline tends t gum up more easily as it ages compared to the regular leaded gasoline of several years ago.  Drain the tank between seasons.
     To get good tight connections, it is best to use new brass fittings and new tubing for the supply line to the fuel mixer.
     The fuel adjustment valve should have a good clean smooth point.  If needed, a new valve can be made from ready bolt or the old one can be put in a lathe and the point redressed.  The valve seat rarely requires attention other than to see that the hole to the supply line is open.
     The accompanying illustration shows some of the features mentioned above.

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