Starting device

Starting device

This enables the engine to be started when it is cold under the most arduous of weather conditions. It is controlled by means of a lever placed behind the gearshift lever and must be progressively adjusted to its normal rest position as the engine reaches the normal operating temperature. The starting device comprises a valve 33 (see FIG 2:5) actuated by the lug of the rocker 36 which is connected to the control lever 38 by a suitable shaft. By pulling the device control fully across through lever 38 and rocker 36, the valve 33 is lifted from its seating and brought into the 'fully open' position. Refer to diagram 'A' (FIG 2:5). Under these conditions the valve 33 closes the air hole 27 and the mixture hole 29 and uncovers mixture orifices 30 and 32 which also communicate with the starting jet 46 through a duct 26 and air holes 35. With the valve 33 partially open the hole 29 may communicate with the carburetter throat through the valve central slot, duct 28 and the hole 31 drilled in the venturi 21 corresponding with the venturi restriction.

When the throttle is set at the idling speed position, the engine vacuum caused by the operation of the starter enables the fuel contained in the recess of jet 46, in the jet and in the reserve well 45 to be mixed with the air coming from holes 43 and 44. The mixture arrives through the duct 26 and holes 30 and 32, at the same time as air passing from the holes 35, past the throttle through duct 34 so permitting easy starting of the engine.

After the engine has fired initially, the device will deliver a charge with a rich petrol/air ratio so as to permit regular running of the engine whilst it is cold. As soon as the engine has warmed up to normal operating temperature this charge would obviously be too rich and therefore it is necessary to gradually ease off the operation of the starting device as the engine reaches its normal operating temperature. During this adjustment the valve 43 slowly uncovers the hole 27 which will permit a greater amount of air to enter through the spring guide hole 42 so weakening the mixture at the same time as closing the progression holes 30 and 32 and air holes 35 the amount of mixture is also reduced. See diagram 'B' (FIG 2:5).

The hole 29, the duct 28 and the hole 31, which are drilled in the venturi 21 permit a regular progression of acceleration whilst the engine is cold as well as when it is at normal operating temperature. By opening the throttle butterfly 19 to increase the speed of the engine the vacuum acting on the duct 34 is decreased. This causes a drop in the amount of fuel delivered through duct 34 with consequent irregular running of the engine but, through hole 31, duct 28 and hole 29 some charge is sucked in by the vacuum formed in the restriction of the venturi, caused by the opening of the throttle and this automatically compensates for the reduction in the delivery through the duct When the starting device is not in operation, valve 33 covers the hole 29 and so preventing the passing of fresh charge. Diagram 'C (FIG 2:5).