Manufacturers of carbureters and ignition devices are called upon to assist in overcoming troubles caused by the inclusion of too many heavy fractions in automobile fuels. So far as completely satisfactory running is concerned, the difficulty of the problem with straight petroleum distillates is caused by the heaviest fraction present in appreciable quantity.
The problems are involved in the starting, carburetion, distribution and combustion. An engine is really started only when all its parts have the same temperatures as exist in normal running, and when it accelerates in a normal manner. Two available methods, (a) installing a two-fuel carbureter, using a very volatile fuel to start and warm-up the engine, and (b) heating the engine before cranking by a burner designed to use the heavier fuel, are described and discussed.
It is pointed out more effort has been made to mix the fuel with air in correct proportion and distribute it among the cylinders than to handle it properly in the cylinders. It appears that knocking occurs later than has been supposed, and is caused by exceedingly high pressure in the engine. The meeting of the new conditions in the cylinders has not had proper attention. The fuel situation makes the problem pressing. A heavy-fuel carbureter-type engine could probably handle some of the lighter fractions of gas and fuel oils.
It should, however, be capable of handling all the fractions, beginning with the gasolines and on down through the fuel oils.


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