The Vaporizing Of Paraffin for High-Speed Motors
(Electric Ignition Type)

30 VAPORIZING OF PARAFFIN. admission valves are regulated by a diaphragm of large diameter, with the purpose as before described of ob- taining a more accurate movement of the supplementary air valve, the larger area thus exposed to the varying depressions in the mixing chamber enabling a greater range of compensating effect to be obtained. In another variant in carburettor design, as for instance in the B.S.A., a variable jet action is obtained by a thimble over the spray nozzle, which is drawn up by the air flow in approximately the ratio of mixture volume supplied to the motor, and by lateral openings simultaneously ■Controls the spray feed. In all apparatus depending on accurate tension adjust- ment of springs, there is an element of uncertainty, and ha ving regard to this, the Scott-Robinson carburettor shown in Fig. 26 has been designed to dispense altogether with the usual spring resistance factor, thereby elimin- ating error due to varying tension, but not that due to friction and momentum of moving parts ; however, the latter effect on the weighted air regulator is not found to materially interfere with its action when applied to a high-speed motor. The modus operandi of this car- burettor is such that the floating piston n is drawn up to a height' determined by the admission of mixture past the drum throttle h, and carries with it a taper pin valve e fitting in the fuel nozzle s, the spray entering the hollow piston, and is thence drawn through a series of holes as shown, and mixes with air as it flows up from the neck-shaped choke passage forming the set of the combined air and fuel regulator piston. In running dead slow with this carburettor, the throttle drum h is nearly closed, and the piston regulator then rests on