Answers to Questions About Engines

Teachable Moments: Updated answers to frequently asked questions about engines at antique engine shows

Gas engine shows provide great opportunities to educate the curious. Be ready to answer their questions!

Gas engine shows provide great opportunities to educate the curious. Be ready to answer their questions!

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In the June 1990 issue of Gas Engine Magazine, Hubert Motry submitted the article “Answers to Spectators’ Questions,” in which he offered concise answers to the most common questions about engines encountered by exhibitors at antique engine shows. The following is an updated version of that article by Kirk Unzelman and Mike Intlekofer of Bellevue, Wash., who have rewritten the answers to be more clear, removed some obsolete references and added a few more questions about engines that they often hear at antique engine shows.

Q. When did gasoline engines first come into use, and what period of time used the old single cylinder or “one-lunger” engines on display here?

A. Although experimented with for a century before this, gas engines were introduced as a potential source of power around 1880. By 1900 they had become very popular. During the period of time between 1900 and the late 1930s, there were approximately 2,000 companies advertising engines for sale, and gas engines were finding widespread use on farms and in industry. In addition, gas engines were competing with steam engines for tractive power (self-propelled vehicles) until about 1920, when gasoline engines took over. In the late 1920s, high speed, multiple cylinder, high compression, lightweight engines made the old single cylinder engines less desirable.

Q. What horsepower ratings were available in these old engines?

A. Most of the engine manufacturers featured a family of engines of various sizes. The most popular were 1-1/2 to 10 HP at a rated speed of about 450 RPM. However, many models producing 40 HP and more were built. During the 1920s, some manufacturers built multiple cylinder engines of more than 1,400 HP. A 2-1/2 HP engine weighed about 250 pounds. A 10 HP engine weighed about 1,800 pounds and had two flywheels 38 inches in diameter and weighing 400 pounds each! Large cylinder displacements were essential to develop reasonable horsepower at the low compression and low speeds that were used. Large flywheels were essential to provide power to the load during the non-productive exhaust, intake and compression strokes.

Q. Why were gasoline engines so popular when electric motors were available during most of this time?

A. Electric motors were available, but electricity to run the motors was not available in many areas. Not until the 1930s was electricity finally introduced to rural or lower population communities.

Q. What were these engines used for that made them so popular? 

A. Wherever a wheel turned or hand power was needed, someone would adapt an engine to do the work. Examples: Pump water, saw wood, grind feed, chop corn fodder, run an air compressor or forge blower, churn butter, separate cream, shell corn, generate electricity, wash clothes, elevate hay, auger grain, press cider, run a hay press, bind wheat, power a line shaft to operate a lathe, grinder or drill press, and many, many more.

Q. How many manufacturers of these old engines are still in business?

A. In the early 1900s, nearly every city had foundries, and at least one foundry would cast, machine and sell a family of gas engines. This is why there were 2,000 manufacturers. As always, technology and shipping improved, and less competitive makers were eliminated, leaving just a few major sources: Fairbanks-Morse, Hercules/Economy/Associated, John Deere, Stover, International Harvester, Sattley, Cushman and a few others. John Deere is the only one remaining as an independent company.

Q. What is meant by the term “hit-and-miss” in reference to old gas engines? 

A. “Hit-and-miss” is a term referring to a speed governing method used to limit and maintain the speed of the engine. In this type of control, when the speed exceeds the set speed, a latch is engaged to hold the exhaust valve open and inhibit ignition. When the engine speed slows down, the latch is released, the exhaust valve closes, ignition is restored and the engine operates in a normal manner until the set speed is exceeded again. A flyball governor is used to sense the speed and actuate the latch. Due to the hit and miss action, the engine skips some of its power strokes, and has varying exhaust sounds as the load varies.

Q. What is a throttle-governed engine?

A. Throttle governing is an alternative to hit-and-miss governing, and is possible on engines that have a carburetor. In this case, when the engine exceeds the set speed, the carb throttle plate is moved so as to reduce the fuel/air mixture admitted to the engine. When the engine speed slows down, the throttle is opened to admit more fuel/air mixture, restoring the speed. A flyball governor is used to sense the speed and vary the throttle. With the throttle governing method, the engine fires every power stroke, despite variations in load.

Q. Why is there no pushrod for the intake valve?

A. Early engine designers used atmospheric pressure to open the intake valve on the intake stroke of the piston, against slight spring pressure. This avoided the cost and complexity of an intake valve cam and pushrod. It also permitted the use of the hit-and-miss governing system.

Q. Why did they eventually change the operation of the atmospheric pressure action to open the intake valve, and replace it with a pushrod and rocker arm?

A. The demand for higher speeds changed the requirements for fuel delivered to the combustion chamber. The old method of piston suction opening the intake valve was too slow in action, and resulted in low compression. A positive valve opening time, duration and closing time, had to be built into the system, so the intake pushrod and rocker were added to the design.

Q. What is low tension ignition?

A. With the low compression engines of the time, a small spark was all that was needed to ignite the fuel mixture. This was provided by an igniter installed in the combustion chamber. An igniter was a device in the combustion chamber that provided a path of flow for an electric current that also passed through an induction coil. At the precise time that a spark was needed, a movable arm and lever on the igniter would open a set of contact points that the current was flowing through. The abrupt break in the path of flow caused a spark, which ignited the fuel mixture. The source of the current was low voltage, either a battery or a low voltage magneto. This was known as a low-tension system.

Q. What are the pros and cons of battery and magneto ignition?

A. A battery ignition system offers simplicity, because it requires only battery, points and a coil (also a condenser for high tension systems). The main disadvantage is the need for a charged battery during the entire running time of the engine. This could be a problem in cold or remote locations, or during infrequent usage. On the other hand, a magneto ignition system requires no battery and is ready for service at any time. The main disadvantage is that it has numerous moving parts, sometimes including a mechanical impulse device for starting, and needs maintenance and adjustment.

Q. What is the difference between a two-stroke and a four-stroke engine?

A. The two and four refer to the number of strokes of the piston to complete a cycle of events within the cylinder of an engine. Most early developers thought that for an internal combustion engine to operate efficiently, it would require four strokes of the piston. The strokes were: an intake stroke, a compression stroke with ignition at the end, a power stroke and an exhaust stroke to eliminate gases. Dr. N. A. Otto and Eugene Langen produced an engine using these principles in 1876. This became known as the Otto cycle or four-stroke cycle, and is the basis for virtually all automobile engines in use today. Nevertheless, that same year George Brayton introduced a practical two-stroke engine. This engine combined the first two strokes, intake and compression, in one, and combined the power and exhaust strokes in one stroke. This engine used port openings in the cylinder in place of the conventional valves. The two-stroke engine dynamics are more complicated than four-stroke cycle engines, but the two-strokes had much better power to weight ratio, resulting in their widespread use in washing machines, drag saws and portable tools.

Q. What is a sideshaft engine?

A. A sideshaft engine, although similar in construction and purpose to any other gas engine, has one major difference. In place of the reciprocating pushrod used on conventional engines to operate the exhaust valve and ignition systems, the sideshaft engine uses a rotating shaft. The shaft ran from the crankshaft to the engine head, and lobes on the rotating shaft operated the exhaust valve and the ignition device.

Q. What is a vertical engine?

A. A vertical engine works on the same principles as a horizontal engine, but is distinguished by having a vertical piston and cylinder arrangement. Usually, the crankshaft is below the cylinder, but some rare models have the crank above. Some manufacturers specialized in making this design, and promoted them based on the smaller floor space needed for use.

Q. What fuel was used in these engines?

A. Although we refer to them as gas engines, these engines were capable of running on a whole range of different fuels. Depending on manufacturer and style, these engines could be made to run on kerosene, gasoline, naptha, vaporizing oil, propane and natural gas. A common configuration was to start the engine on gas, then switch to kerosene.

Q. How were these engines cooled?

A. The majority of the engines were water-cooled, generally with a hopper full of water, which mixed by natural convection. A few water-cooled engines used a circulating pump and screens, cascades, or fin and tube radiators to shed the heat. When running near rated horsepower, the water would heat to the boiling point and create steam. The escaping steam required that the water be replaced frequently. Some engines were air-cooled, by means of fins on the cylinder heads, generally using a fan powered from the crankshaft. Air-cooling avoided the hazard of having cooling water freeze in the winter, cracking the cylinder casting. A few engines used oil as the coolant, which permitted them to run at a high temperature and improved efficiency when running on low grade fuels.

Contact Mike Intlekofer at 4472 119th Ave. SE, Bellevue, WA 98006 • 

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