Craig

Craig Miller, W8CR

4/1000 of an Inch

.004 of an inch, that’s all it took to get 2,000 pounds of cast iron flywheels spinning. Simple as that, why did it take so long to figure that out? It took me a bit over 30 years. Long, long time ago, in a galaxy far, far away, I thought it’d be cool to buy a really big, heavy, old engine. Ya can do those things when you’re not married and no kids to feed. It sat lonely next to an abandoned farmhouse about to be bulldozed. This relic needed a home and some TLC. It’s a Bessemer, 22 ½ HP , 10” piston, 15”stroke (1,178 cubic inch displacement!) hit-n-miss engine, Two 6’ flywheels, weighing a 1,000 lbs each, 5,400 lbs in total - heavy. Its original gig was to power the see-saw type pumps in the oil fields of Pennsylvania (remember Quaker State Oil?). It was built in the 1920’s and ran on natural gas which was plentiful off of the well heads. Nowadays, the wells (what few we are allowed to keep running) use electric motors and these big beauties were put out to pasture. Sadly, some were dumped in scrap yards, no “thank you” for years of faithful service, you’re junk to me now. Fortunately, some were salvaged from the cutting torches to live another day. This baby is serial number 38,054. I actually have a copy of the original production card which is somewhere in my extensive filing system (shoe boxes). I recall its birth date was some time in 1924. They don’t change much from year to year. It does use a Wico magneto, which was pretty high tech for the day. After attending the Miami Valley Steam Thresher’s Reunion in Plain City this summer where several similar engines are on display, I became motivated to get the bad-boy up and running with hopes of showing it next season. After sitting dormant for over 30 years, a good going through is in store. Two new 100 lb propane tanks and high-flow regulators were the start. Cleaning and adjusting the magneto was also in order. It generates a healthy spark, so that is good. The mag is a simple but very effective device. A couple of bar magnets and a laminated iron core. When the armature breaks contact by the pushrod driven off of the crankshaft, a magnetic field collapses, sending current through a secondary set of coils producing a gee-wiz spark. All in place, let’s take her out for a drive. The machine is started by compressed air, pushing the piston to get the fly-wheels spinning. It’d perk and then die. Readjust gas mixture, spark timing, pray to the gas engine gods, nothing worked. Ole rule of thumb, engines only need fuel and fire to run. I ensure we have plenty of fuel and as far as I can tell, the magneto is generating plenty of fire, so what’s the deal? After a week or two of hitting my head against the wall wondering why the poor thing doesn’t run right, I determine I must not be getting consistent spark. A trip to local Harbor Freight store, I picked up a $3.99 neon sparkplug testing light. These are very simple devices but can diagnose a fickle ignition system by a small neon light bulb. The brighter the flash, stronger the spark plug is sparking, dim or no flash, the plug is not arcing appropriately. Using the new diagnostic tool, I observe when the engine fires, the light flashes bright. As the engine speeds up, the flash gets dimmer and dimmer and then, nothing, engine dies. Going through the magneto, again, showed nothing wrong – it’s working, so what is the malfunction? You gearheads know that higher the compression, higher ignition voltage or smaller spark gap is required. Since I couldn’t increase the magneto spark voltage, without upgrading to a more modern ignition system, I opted to reduce the sparkplug gap from .030” down to .020”. This improved things, the engine ran better but still died after several revolutions. The cheap neon light again showed no spark when engine is up to speed. I’m about ready to drag this thing to the junk yard, I’m out of ideas. Defeated! The neon light was still telling me something, no fire, all of the time. Nothing to lose, I pulled the plug out and reduced the gap between the electrode and ground to .016” and tried again. This time it fired up and ran flawlessly, purring like a kitten, as far an oil pumping engine can. .004” is all it took, basically the thickness of a few sheets of paper is all this machine needed to bring it back to its glory days. In hindsight, as the engine sped up, being a two- stroke, the cylinder compression increased to a point where the magneto wasn’t able to generate enough energy to get a spark to jump the gap, igniting the air/fuel mixture. Tightening things up did the trick. The exhaust note is rather, shall we say, explosive. Not wanting to cheese off the neighbors, I built a simple glass-pack muffler to knock down the loud crack of exhausting combustion. A five-gallon metal bucket, fiberglass and metal screen did the trick. So what do I do with it now? I call it a BDM. Start it up, drink beer and watch it run, a Beer Drinking Machine! A goal is to hook up an electric generator to the flywheels to provide power to run an amateur radio station. I hope to put this on display in the next Steam Thresher show and run a special event station, powered by this beauty. Maybe Field Day too, why not? As I always say, Ham Radio makes everything better.