Hercules Engine News
20601 Old State Road Haubstadt, Indiana 47639
On the 1-2 HP Hercules built engines, there are seldom problems
with the crankshaft unless it has been bent, severely worn or badly
rusted. If the shaft is bent, it usually can be straightened in a
press with a little trial and error. However, it may be easier or
less expensive to find a suitable replacement crankshaft. Normally
the crank-shaft won’t bend unless the engine is dropped or
bumped hard. Even though the length varies somewhat between models,
the 1 inch diameter crankshaft will interchange along with the
Even though bearing surfaces are worn or scored, they usually
cause no problems especially if new bearing inserts are used. The
main bearing surfaces seldom wear out of round; however, the
connecting rod bearing surface may at times. Even though the
connecting rod bearing surface may be a few 1/1000th out of round,
it usually causes no problem on slow running show engines. Just
keep the adjustment snug. If the surfaces are scored, new bearing
inserts will usually be all that is needed; however, they may
require adjustment from time to time until they become ‘worn
in.’ New babbitt bearing inserts are available from several
suppliers. Occasionally someone reports that their engine has
poured bearings. Not so. Originally all of the small block engines
had poured main bearing liners in the casting, but they were the
base for the replaceable bearing insert.
If the crankshaft bearing surfaces are rusted and pitted, the
shaft is generally still usable. First clean off all the rust
possible then use a strip of emery cloth to shine up the shaft as
much as possible. Use Devcon Epoxy Steel or JB Weld to fill the
pits and file down to the original surface and then use emery cloth
to smooth it up. Surprisingly, this works pretty good.
The original shims were some combination of steel and cardboard.
I make thick shims from head gasket material and the rest from
whatever cardboard that is handy. Start out by tightening the
bearings until they bind and then back off about turn. Actually,
for a slow running show engine, main bearing fit is not very
critical. Especially on the rod bearing, locknuts should be used.
Be sure that the stud bolts are tight in the rod. If the engine
begins to clatter after it has run for some time, it is likely that
the rod bearing needs to be readjusted.
There should be very little endplay in the crankshaft main
bearings. At times it may be necessary to loosen the flywheels and
push them in a bit.
On engine models with only about one inch of crankshaft showing
on the cranking side, it is very important that the flywheel key
sticks out far enough for the hook type hand crank. The key should
also be square and unworn where the hand crank engages. A
combination of too short of a key with a worn surface is apt to
cause the hand crank to slip off while cranking the engine. If the
hand grip on the crank is free to rotate, you may get hit in the
arm, chest or head by the free swinging crank. I speak from
Coming up next time is the fuel system.
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