Gas Engine Magazine

Hercules Engine News

By Staff

20601 Old State Road Haubstadt, Indiana 47639

In these next several articles, the Hercules Engine News will
cover various adjustments and repairs to keep Hercules built
engines functioning correctly.

 First, let’s begin with the general tune up procedure.
The first step is to make sure that the cam gear is properly timed.
The timing gear has a ‘V’ type notch cast near the gear
perimeter. The instruction books indicate that this mark should be
lined up with the flywheel key. Align the center of the crankshaft,
the flywheel key and the spoke straight out from it with the center
of the cam gear shaft. At this point the timing mark should be
centered behind the flywheel spoke. In other words, the timing gear
mark (1), the cam gear center (2), the flywheel spoke (3), the
flywheel key (4) and the crankshaft center (5) should be in a
straight line. The diagram at right is an easy way to make this
check. All sizes of Hercules built engines are timed this way.

If it is necessary to change the timing, it is easiest to take a
long punch and push the timing gear shaft out so the gear can be
turned to the correct setting.

Once the timing gear is properly set, it is time to check and
adjust the exhaust valve. This setting is done by adjusting the
screw and lock nut on the exhaust valve rocker arm. According to
the instruction books, the exhaust valve should begin to open at 45
degrees before outer dead center on the exhaust stroke. It should
close 3 to 5 degrees after inner dead center just at the beginning
of the intake stroke. The exhaust valve setting on all sizes of the
Hercules built engines is done this way.

After the timing gear and the exhaust valve settings are made or
checked, then the proper ignition setting can be made. That
procedure gets a little more complicated and will be covered next

  • Published on Jan 1, 1995
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