Timeline of the Fairbanks-Morse Z Engine
For the February/March 2018 issue of GEM, regular reader Jim Albaitis sent us color copies of an original 1916 United Engine Co. brochure, which we displayed with an article on United Engine Co. penned by Dick Webber.
For this issue, Jim sent yet another color brochure, this time for the Fairbanks-Morse Z engine line. Highlighting the 1-1/2 hp, 3 hp and 6 hp engines, the brochure was most likely produced in 1923, the year F-M introduced the “Battery Equipt” hit-and-miss version of the 3 hp Z. The 1-1/2 hp Battery Equipt Z was introduced in 1922.
The following Fairbanks-Morse Z engine timeline was penned by then 10th grader Wayne Grenning and published in the July/August 1981 issue of GEM. It was his first article to appear in this magazine, and Wayne appreciates that in his youthful exuberance he may have gotten a few facts wrong, chiefly the introduction of the Z series, which he dated to September 1916: It’s believed to have been introduced two years earlier, in July 1914. Further, as Wayne later appreciated, Fairbanks-Morse never made a 3 hp or 6 hp headless Z engine. Finally, Wayne’s original article referenced the 1-1/2 hp Z as a 1 hp. That has been updated here. – Editor
F-M Z timeline: The Technical History of the Fairbanks-Morse
This is written to help Fairbanks-Morse collectors. Original manuals, catalogs, documents and reprinted sales literature were used. For this article only 1-1/2, 3 and 6 hp engines will be discussed.
The Fairbanks-Morse Company was founded in the late 1880s with headquarters in Chicago, Illinois. Fairbanks-Morse manufactured many kinds of engines including the Eclipse Pumper, Jack of all Trades and many industrial engines. In September 1916 the Z series was introduced. [Engine historian C.H. Wendel dates the introduction to July 1914, which Wayne believes is actually the correct date.] In the following paragraphs and figures the development of this style will be outlined. Development of the Z engines will be described chronologically through the years 1916 to 1944.
In September 1916 (Number: 200,000) Fairbanks introduced a new engine line, the Z series. The 1-1/2, 3 and 6 hp engines were headless [the 3 hp and 6 hp were in fact not headless, as Wayne later discovered], with valves and igniters on the governor side. Headless describes a type of casting in which the cylinder and head were cast with the crankcase body as one unit. Rotary Sumter magnetos were used on these early Z engines and were driven by the crankshaft gear. Headless construction for all models was short lived because of the difficulty of overhauling and take down of the engine. Headless engines were characterized by a governor located on the upper left side of the cam gear.
Figure 1: Early Z with crankshaft-driven Sumter magneto.
An improved model of the Z series was complete in January 1917 (Number: 260,000), just four months after the first Z series. New 3 and 6 hp engines were made with removable heads. [The 3 and 6 hp always had a separate head.] Location of the magneto and governor remained the same as the first version. On this model, as well as all future models, the gas tank was located within the base. An exception to this practice, were those engines with a partial base. The carburetor and exhaust outlets were changed to the head. The carburetor was on the side, while the exhaust was on the bottom of the head. At first this type Z engine used a water injector to cool it while operating. Later, it was taken off because of too many poor starting engines and fouled igniters.
Next, a change was made in June 1917 (Number: 295,000). The difference between the January and June versions can be seen in Figures 1 and 2. On the 3 and 6 hp engines the magneto and igniter were mounted on a cast iron unit. Magnetos used remained Sumters. Instead of having the magneto driven by the crankshaft gear, the design was changed to an oscillating magneto with a trip and springs. (When the magneto was tripped a lever on the end of the armature hit a movable contact arm and separated the contact points.) This method was useful because it was self-timing. The 1-1/2 hp engine still remained a hit-and-miss.
Figure 2: Mid-1917 3 hp igniter-fired Z with Sumter Plugoscillator magneto.
Another change in the development of the Fairbanks-Morse Z series took place in the latter part of 1918 (Number: 340,000, see Figures 2 and 3.) On 3 and 6 hp engines ignition was changed from igniter to spark plug. Spark plugs eliminated problems of cleaning igniters and retiming when removed. Fairbanks-Morse at this time introduced the American-Bosch oscillating high-tension magneto, which was triggered by a peg on the cam gear. Location of the magneto was above the cam gear while the plug was mounted on top of the head.
Figure 3: Late 1918/early 1919 spark plug-fired 3 hp Z with American-Bosch oscillating high-tension magneto and bottom-exiting exhaust.
The exhaust was switched from the bottom to the side opposite the governor (Figures 3 and 4). The carburetor on this engine had a starting reservoir, which was filled with gasoline or alcohol. While running off of this fuel source it warmed up, then it was switched over to the working fuel, most likely kerosene. A flutter valve was introduced on this model. It provided a vacuum in the carburetor and drew fuel without the use of a pump. In the early versions of this model, Fairbanks-Morse again tried the use of the water injector to cool the engine, but as before water leaked into the carburetor when the water valve remained open. Location of the governor was changed to the lower left of the cam gear. The hopper was cast separately from the cylinder. Two reasons for this were to allow for cleaning of the water jacket and for ease of manufacturing. The 1-1/2 hp model was finally changed from hit-and-miss to throttling governor. Hoppers on the 1-1/2 hp model were not removable. All Fairbanks-Morse Z’s from this date on were of the throttling governor type.
Figure 4: 3 hp Z with side-exiting exhaust.
Further developments on the Fairbanks-Morse Z series were made in 1926 (Number: 672,000). The 1-1/2, 3 and 6 hp engines were equipped with the Fairbanks-Morse high-tension rotary Type R magneto, which replaced the American-Bosch models (Figure 5). The governor bracket which mounts the magneto was changed from cast iron to white metal. White metal lowered costs, as it was the goal of Fairbanks to make engines more competitive in price. Location of the carburetor and exhaust port remained the same as before. Solid disc flywheels now appeared on the 1-1/2 hp models.
Figure 5: 1925 6 hp Z with Fairbanks-Morse Type R magneto.
In 1929 (Number: 727,000) 3 and 6 hp engines were changed very little. A small change occurred in the location of the drain plug, which was changed from the front of the cylinder to the rear. Also, the gap in the water jacket was widened for increased cooling. 1-1/2 hp engines were designed with a crank handle in the flywheel face. Oilers were changed from brass and glass to steel without a sight.
Figure 6: 1-1/2 hp Z Style D of the type built from late 1928. This particular engine is set up for running on natural gas.
In 1932 (Number: 777,000) the magneto was changed from a high-tension Fairbanks-Morse Type R to a Fairbanks-Morse Type J. The R had a copper-wound armature which rotated inside a magnet. The J had an armature which rotated inside a copper wound coil. On all of the Z engines (1-1/2, 3 and 6 hp) the lubrication was changed from grease to oil. An oil reservoir in the bottom of the crankcase in conjunction with a splasher oiled all the internal parts. Horsepower ratings were changed to higher rpms. For example, the 3 hp was raised from 475 rpms to 650 rpms. Also, on this model the diameter of the flywheel was decreased from 22 to 19 inches. Improvements made in the carburetor allowed less fuel to be used, and it was smaller. The flywheels on the 3 and 6 hp remained spoked. In 1932 [C.H. Wendel says late 1928] the 1-1/2 hp engine was reduced in size with fewer exposed parts and looked more like a box with two flywheels (Figure 6).
Final developments in the Z series saw larger diameter flywheels. The last Z’s were manufactured at the close of World War II (Figure 7). Almost all of the Fairbanks-Morse Z engines were painted grass green with machined flywheel surfaces; however, a few were painted red.
Figure 7: 1941 3 hp Z (designated ZC-52) with post-1940 F-M logo.
Gasoline, kerosene, alcohol, coal oil, oil tops and other low-grade fuels were commonly used. Z’s were originally sold with air compressors, vacuum pumps, water pumps, corn shellers, light plants, feed grinders, food cutters, power heads, washing machines and saw mills. Often they were purchased by a farmer for multiple uses around the farm. Over 550,000 Z engines were manufactured.
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