Fig. 40 shows the Carter carburetor which embodies a radically new principle. It belongs to the multiple-jet type, but possesses this striking difference, variations in fuel level are utilized to determine the number of jets in action at any time. The variations in fuel level occur in a vertical tube known as the “stand pipe.” They take place in instant response to the slightest change in the suction exerted by the engine. As this suction depends directly on the engine’s speed, it can clearly be seen that this provides a marvelously sensitive means of automatic control. A large number of exceedingly small jets are bored spirally around the upper portion of this tube. As a result, the level at which the fuel stands within it, determines the number of jets from which delivery is being made at any instant and the gasoline supply is always directly proportioned to the engine speed, however suddenly changes in speed take place. Owing to the comparatively large number of these jets, their exceedingly small size, and their correspondingly short range of action, the flow of fuel is absolutely uninterrupted.

The instrument is permanently adjusted for low and intermediate speeds at the time of installation. An auxiliary air valve controlled from dash or steering post forms the high speed adjustment as well as affording a means of securing absolute uniformity of mixture under widely varying conditions of weather, temperature, or altitude, directly from the driver’s seat. A simple method of enabling each cylinder to such a rich priming charge direct from the float chamber is another valuable feature that obviates all need of priming and insures easy starting in the coldest winter weather.