A major advantage obtained from combining the fuel pump and injection valve is the ability of an engine so equipped to burn a wide variety of fuels. The elimination of the above-mentioned type of high-pressure tubing reduces the possibility of a vapor lock occurring, thereby permitting more volatile fuels to be burned. This increases the range of hydrocarbon fuels the engine can utilize. It could run on any type of hydrocarbon from gasoline to melted butter.[15] Another reason for combining the fuel pump and injection valve is given by P. E. Biggar in _Diesel Engines_ (published in 1936 by the Macmillan Company of Canada Ltd., Toronto): "In the Dorner pump, for example, the stroke of the plunger is changed by using a lever-type lifter and moving the push-rod along the lever to vary its movement. Unfortunately, in all arrangements of this sort, the plunger comes to a reluctant and weary stop, as the roller of the lifter rounds the nose of the cam. When the movement does finally end, the injection does not necessarily stop, as the compressed fuel in the injection pipe is still left to dribble miserably into the combustion chamber. To minimize this defect, the designer has placed the pump and injector together in a single unit." [Illustration: Figure 30.--Mechanism for retarding valve and fuel-injection timing during starting (see also fig. 26). U.S. Navy test, 1931. (Smithsonian photo A48324E.)] [Illustration: Figure 31.--Upper--valve and fuel injector cam; lower--fuel-injector cam used for starting. U.S. Navy test, 1931. (Smithsonian photo A48325.)] Starting System: On November 1, 1961, C. H. Wiegman, vice president of engineering of the Lycoming Division of Avco Corporation wrote to the Museum in part as follows: