Fig. 1: Governor and throttle assembly
Wayne Grenning of 318 Summit St., Boonville, N.Y. 13309, wrote the following history of the International 'M' engine, which will be continued in the Nov./Dec. issue of GEM. Wayne is a freshman at Alfred State College (TV. Y.) where he will major in internal combustion engineering technology. He currently serves on the board of directors of the Flywheels & Pulleys engine club at Constable ville, N. Y.
International has been the maker of a vast variety of farm products including: hay balers, combines, plows, ensiligers, potato diggers, and gasoline engines. It is the type 'M' engine that is of concern here. International manufactured many different style engines of all horsepower including among others: the Famous, Tom Thumb, Titan, Mogul, L, LA, LB and the 'M'. A basic description of the construction, characteristics, and chronology of the 'M' series follows.
International engines were manufactured in the 'Milwaukee Works' at Milwaukee, Wisconsin and the McCormick Deering 'M' engines in the 'Deering Works' at Chicago, Illinois. In this article the International Harvester 'M' and the McCormick Deering 'M' are considered the same. They were manufactured between 1917 and 1937.
The type 'M' was related to the smaller size 1,1?, and 2 horsepower earlier mogul engines. Many similarities between the two types are apparent. The governor, breather, magneto, ignition system, fuel system, enclosed crankcase, and air cooled heads (on 1? and 3 horsepower engine) are all from the same inspiration. It has been said the International 'M' series were modified Moguls with similar parts, lighter construction and higher R.P.M's per horsepower. 1? and 3 horsepower 'M' engines were manufactured with air cooled heads. At the same time the 6 and 10 horsepower models were equipped with water cooled heads because of vast quantities of heat generated under full load.
All 'M' engines were offered as stationary units, on skids or trucks and were painted a satin 'Grass Green' finish except for the rim of the flywheels. Fancy pin striping commonly used on earlier International engines was eliminated on the 'M' series because it helped reduce the price. The 'M' series was distinguished by its one piece enclosed crankcase block, allowing for a clean engine and improved safety. An access hatch on the rear of the crankcase was a necessity for the removal of the connecting rod and piston from the crankshaft. Speed was regulated by a governor which was located on the P.T.O. side of the engine. Two opposed weights were located between spokes of the flywheel. Centrifugal separation of the weights by acceleration of the engine caused a sliding sleeve to move on the flywheel hub. Motion of the sleeve was captured by a rod located on the side of the engine. The other end of the rod was attached to the throttle plate located on the upper part of the cylinder head (see figure 1).
All 'M' engines had cast iron cylinder sleeves (see figure 2). These were of the wet liner type, meaning that the sleeve was the cylinder and cooling liquid was in direct contact with it. Fuel was pumped to the carburetor by means of a piston type fuel pump, operated by motion from the cam eccentric. International designed their 'M' engines with the fuel pump at the same level as the fuel tank. As a result, the pump would always be primed for the next running.
All International Harvester 'M' engines were built with the fuel tank located within the lower portion on the base and were made of galvanized sheet metal. The filler pipe could be located on either side of the engine depending on its application. All 'M' engines were of the throttling governor type. 'M' engines were one of the only farm units using a connecting rod grease cup mounted on the end of the crankshaft. Left hand threads were used in order that as the shaft turned, squeezing of the cup would allow the connecting rod to be lubricated (see figure 3). Even though the series used the enclosed crankcase system, all babbit bearings were lubricated with grease cups. R.P.M. ratings on the 1?, 3 and 6 horsepower engines ranged from 550 to 650.
The 1? horsepower 'M' was in production from 1917 to 1933. It was of the kerosene type with two needle valves. Gasoline was poured into the single starting reservoir of the carburetor. As the engine ran, kerosene was pumped from the tank to the reservoir of the carburetor diluting the gasoline and increasing the concentration of kerosene. Excess fuel was drained back into the fuel tank by means of an overflow hole built within the carburetor. With this system, the longer the engine ran the higher the level of concentration of kerosene in the carbuertor. The carburetor was cast in one major piece with the needle valves, choke and venturies fitted later. Unfortunately, the carburetor could not be taken apart for cleaning. At first there were two needle valves, whereby fuel was adjusted by the needle valve on the magneto side. Water injection was adjusted by the needle valve on the governor side. The use of water prevented the loud pounding and bearing wear of a hot, kerosene burning engine. Water for this purpose came from the hopper.
1917 engines used the rotary type 'L' low tension magneto in combination with the ignitor for ignition. Ignitors of the 1? horsepower engines were on the magneto side of the head. The magneto consisted of two magnets, a copper wound armature, an aluminum name strap used to hold the magnets on the magneto frame, a white metal frame, a bearing plate, and a contact tower for the. electricity (see figures 4 and 5). The cam gear was used for driving the 'L' magneto. The engine was rated at 650 R.P.M.'s and 122,484 units were built with the low tension rotary magneto.
In 1923 options were offered. An engine with a gasoline carburetor was now available. In this case, only one needle valve was supplied with a choke and overflow. It was a great success because of its simplicity. For starting, the operator filled the starting reservoir chamber with fuel and turned the flywheels. The water needle valve was not added to this engine because gasoline did not burn as hot as kerosene. It remained an optional feature on the 1? horsepower unit until production ceased in 1933. Another option offered was the choice of high tension (spark plug) ignition. High tension current was supplied by a cam gear driving a rotary American Bosch type 'S' magneto. An impulse mechanism on the magneto allowed for easier starting with lower cranking speeds, and uniform spark at all R.P.M.'s. Although the American Bosch type 'S' magneto for the gasoline 1? horsepower engine was offered, only 11,100 were sold between 1923 and 1924. An additional 2,000 kerosene engines with the American Bosch magnetos were sold between 1923 and 1932. R.P.M. ratings were also lowered from a high of 650 in 1917 to 500 in 1923.
The rear crankcase access hatch was changed. On 1917 models, a large wingnut located on the center of the plate was used to attach it to the engine. The long flat cast iron bar which caught an ear on the inside of the crankcase was replaced in 1923 with a plate and four machine bolts (see figures 6 and 7). Many complaints of hatches falling off of the engine from vibration were reason enough to change the mounting method.
Another needle valve was added to the kerosene carburetor which was now cast in two pieces, thus allowing for take down (see figures 8 and 9). This later version of the carburetor was preferred for many reasons:
1) There were separate chambers for gas and kerosene. 2) Kerosene would not dilute the gasoline before the engine warmed up. 3) With this system, kerosene was pumped into its own chamber and returned to the tank when the proper amount of fuel was reached within the carburetor. In this manner the operator could make the decision and manually change the fuel from gasoline to kerosene. 4) It was equipped with individual drain holes in each chamber.
About the middle of 1923 International changed the three needle valve heads on their new carburetor from iron to white metal. The fuel pump was also changed from cast iron to white metal. The fuel outlet on this new model was at a 45 degree angle instead of horizontal as used on the earlier type (see figures 10 and 11).
In 1929 the type 'L' rotary low tension magneto and ignitor were replaced with the ever popular 'Wico EK High Tension Magneto.' (see figures 12, 13 and 14) A more sophisticated device, the spark on the Wico could be delayed to prevent back firing and injury. The
spark plug was located on the left side of the head and the ignitor with its associated parts were removed. 7/8 inch thread were used for the spark plug unlike the ? inch threads used on earlier International engines. Like the American Bosch Magneto, the Wico supplied a strong spark at all engine speeds. From 1924 to 1933 the 1? horsepower engines were offered with the Wico EK.
One further significant change was the removal of the thumb screw speed changer. Removal of this device was needed because many people received hand injuries from the governor and flywheels while attempting to adjust the engine speed as it ran. It was not a very convenient location. Speed adjustment on the 1924 engines was made on the idle engine, by increasing or decreasing the tension of the governor springs.
Because of the location of the new high tension magneto the relocation of the cam gear grease cup was necessary. It was now mounted on the side of the cam shaft bearing under the crank shaft bearing.
In 1933 the fuel pump changed completely on the 1? horsepower units. Now a diaphram type with a glass fuel trap was standard equipment. Up to its withdrawal in 1933 a total of 263,144 International 1? horsepower type 'M' engines were built in 16 years of production from 1917 to 1933.
Next issue this story will continue, tracing development of the 3, 6 and 10 hp models.