Page 27 - Demo

Page 27.Alvis Three Litre Shop Manual - T.A. 21 and T.C. 21suction that it is hermetic. If not, gently tap the needle on its seating, which will probably correct it, but do not grind in, for this will permanently injure it.Caarbuburettttor FiiltterA cylindrical gauze filter is provided at the union of the petrol pipe and float chamber to prevent the ingress of any foreign matter. The union should be unscrewed and the filter cleaned at regular intervals.Caarbuburettttors - Twi win SS.U. wit with Thermmostatic tatic Caarbuburettttor Attac ttachmmenttLater models of the Three Litre engine are fitted with twin S.U. Carburettors with an electrically-operated auxiliary carburettor for easy starting from cold, the general layout of which is illustrated on page 26.The main components of each carburettor consist of a piston carrying a taper jet needle which protrudes into the orifice of the adjustable jet itself; thus when once the carburettor has been set at idling speeds, it should be correct throughout the entire speed range of the engine. Above each piston is a hydraulic damper to prevent piston oscillation, which in turn prevents spitting back. It is most important to maintain a damper chamber half full of engine oil, specification SAE.20. The damper plunger is attached to the oil cap nut and comes away with the nut when it is unscrewed. When replacing the plunger, press it down slowly without using excessive force.The oil in the damper chamber should be replenished every 1.000 miles.SStatarti tingg ffromm ColdTo facilitate starting from cold an electrically-operated auxiliary carburettor is fitted; this is controlled thermostatically. However, the control knob marked %u2018C%u2019 on the facial panel overrides the operation of the solenoid if required.It is pointed out that once the engine has reached the temperature at which the thermostat operates, it is not possible to further enrich the mixture by operating the control knob marked %u2018C%u2019.To start from cold pull out the control knob marked %u2018C%u2019, press the starter switch, without operating the throttle, and when the engine has run sufficiently for the temperature to rise, the auxiliary carburettor will automatically cut itself out.In warm weather the owner may wish to dispense with the enriched mixture before the thermostat would normally operate. The return of the control knob marked %u2018C%u2019 to closed position will achieve this effect. Adjuusti tingg tthe Twi win CaarbuburettttorsThe carburettors are correctly adjusted at the Works and no further adjustment to the jet adjusting screws is advisable or necessary. If, however, the adjustment of the carburettors has been altered for some reason, the following instructions should be observed.Before attempting to adjust the carburettors, slacken the clamping bolts on the universally jointed connections between the throttle spindles so that the two carburettors are entirely independent of each other. Remove the suction chambers and see that the needles are located in the same position in both pistons and that the jets are the same distance below the bridges of the carburettors when they are pushed hard against their adjusting screws.Unscrew the throttle adjusting screws until they will just hold a piece of thin paper inserted between the adjusting screw and the stop lug, then screw in one complete turn. The engine may now be started. When it is thoroughly warmed up the speed may be adjusted by turning both throttle adjusting screws equal amounts in either direction, depending on whether a higher or lower speed is required. To check for exact synchronisation of the throttle opening it is best to listen to the intake. If the hiss on one of them is louder than the other unscrew its throttle adjusting screw until the hiss is equal. When it is obvious that this is satisfactory the mixture should