It Runs!  After 3.5 years of putting in ~12 hours a week at the Barrow High School Shop, minus summer breaks, burn-out periods and computer rebuild time, it is running!!  (Spring 2000)

On the movie, the sound is a little "tinnier" than in real life, but the engine is suprisingly quiet.  The finger snap, pop, like sound is the actual firing, the other clickity-clack sounds are the push rods, valves and such moving back and forth. 

It may not be as precise or pretty as Philip Duclos', but I'm happy with it.  Especially considering that the only prior thing I ever made on the metal lathe and/or milling machine was a brass mallet.  I will admit that I made quite a few "practice" parts.

Six-Cycle OddBall
Gear and Push Rod Side
Top View
Manifold view
Governor View
Click Here to see the 1.37Mbyte, 1 minute Movie.
Designed and first built by the late Philip Duclos, master machinist and long time contributer to "Home Shop Machinist".

Six cycle means the piston makes six strokes (in and out would count 2 strokes) for one complete engine cycle.  The spark plug only fires once every six strokes, or 3 revolutions.  The "extra" strokes (compared to a 4 cycle/stroke) occur when the exhaust valve opens, the exhaust valve is held open for a total of 3 strokes (4 cycle engines have the exhaust valve open for only 1 stroke).  These extra exhaust strokes help cool the engine and help to
flush out the "stale" air in the cylinder.

The uneven firing rythum is caused by the Govener.  The govener limits the speed.  When the engine rotates too fast, the weights swing out, pulling the lever arm on the side, which pushes a lever under the cylinder into a slot in the exhaust valve push rod, holding the exhaust valve open.  The engine can't draw in fuel or make a compression stroke when the exhaust valve is open, so the engine "coasts" until it slows down. When the govener slows,
it releases the exhaust valve so the engine can fire again.
Six-Cycle OddBall Engine
The intake valve operates by vacuum only.

Runs at about 750rpm.

The fuel is gasoline.

Over all length, minus spark plug, is about 9.5 inches.  The fly wheels are 4.5 inches in diameter.

Bore is 0.75" and stroke about 2", making it
about 0.88 cubic inches.

I estimated the Indicated Power (calculated, doesn't
include friction) to be 0.056 horse-power, assuming
compression of 100psi.

No, it doesn't go in anything or run anything.

I machined and made most of the parts, including
the springs, EXCEPT:

2) Piston rings.
3) Sintered Bronze Bushings.
2) Gears (I had to greatly modify them).
1) Spark plug.
1) Set Points and Condensor.
   most of the screws and bolts.

The majority of the engine parts are made of
cold-rolled steel, except:

  1) Cylinder Head
  1) Govener Bracket
  1) Piston
  1) Muffler
  2) Valve Spring Retainers

  2) Govener Weights
  1) Oiler and Oiler Valve
  (the thing on top of the cylinder)
  1) Fuel Needle Valve Unit
  1) Large Gear

Cast Iron:
  1) Piston Cylinder

Music Wire:
  2) Valve Springs
  1) Govenor Spring

Special Thanks to:
Tom Murphy
Paul Johnson
Dan Endres
Jim Ehramjian

Links Other
Six-Cycle OddBalls
Ralph Jenson
Gene Hehl
Copyright © 2000-2011, Malcolm Gaylord, All rights reserved.
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