Sole Solex Carb Carbur uret etto torr
PARTS NOZZLE VENTURI THROTTLE VALVE MAIN JET FLOAT CHAMBER STARTER LEVER CHOKE TUBE EMULSION TUBE AIR CORRECTION JET CONVENTIONAL FLAT DISC STARTER PETROL JET PILOT JET AIR BLEED ORIFICE VOLUME CONTROL IDLE PORT PUMP INJECTOR PUMP LEVER PUMP INLET VALVE
WORKING
PRINCIPLE
In old days, Fiat cars are most popular brand in India due to its very easy start in cold conditions. This easy start is obtained by Solex Carburetor which is a down draft type carburetor and has special provisions to supply, richer mixture at starting of engine and weaken it gradually till the engine reaches its normal running speed. Solex Carburetor are available in many designs and all have following work circuits, 01) Starting Circuit:The throttle valve remains in closed position during starting . The petrol is supplied to the starter petrol jet through f irst passage from the float chamber and the air through the starter air jet for starting operation. Starting Valve which have different sizes hole, is made from flat disc. The position of various holes can be adjusted in front of starter petrol jet by starter lever and then air is mixed coming from starter air jet .This air-fuel mixture , passes through another holes of starter valve, in a passage of the carburetor, below the throttle valve. The suction stroke of the engine sucks this mixture into the cylinder. This mixture is rich enough to start the engine. After the engine starts and speed increases, a weak mixture is required, therefore, a small hole of the starter valve is brought in front of the starter petrol jet by means of starter lever, there by reducing the quantity of petrol, which weaken the air-fuel mixture. Similarly next smaller hole of the starter valve is brought in front of starter petrol jet till the engine attains its normal speed then the starter valve is closed by bringing the starter lever to its off position. 02) Normal Running Circuit:At normal running speed, starting circuit is closed and throttle valve is opened. The normal running circuit consist of main jet which receives the petrol through second passage, from the float chamber as the throttle valve is opened suff iciently, the air is drawn through the venturi where the petrol mixes up with it forming a suitable mixture for the normal running of the engine. In this case, only throttle valve, governed the air-fuel ratio. 03) Accelerating Circuit:The engine requires an extra rich mixture, during acceleration period . To obtained extra rich mixture, the fuel is pumped under pressure into the main air passage or in the venturi through an in jector. Diaphragm pump is used to create pressure, which is actuated by a lever connected to the accelerator . The pump sucks the petrol from the float chamber through the pump valve and forces it through third passage into the main passage through an in jector above the venturi of the carburetor. 04) Idling And Slow Running Circuit:During the idling operation, the throttle valve is kept closed and the engine receives the mixture through a port opening below the throttle valve, whose area can be varied by an idle adjusting screw according to the need of the engine. The petrol is supplied to a pilot petrol jet from the main jet fuel circuit through fourth passage and the air from a pilot air jet .The petrol and air thus supplied mix up in the idle passage and go to a port s ituated below the throttle valve from where the mixture is sucked by engine. During the slow running , the engine draws the mixture from the idle passage through a hole situated above the throttle valve when the
SOLEX CARBURETOR
DIFFERENT PARTS A nozzle is a device designed to co ntrol the direction or character istics of a fluid flow(especially to increase velocity) as it exits (or enters) an enclosed chamber or pipe via an orif ice. Fixed venturi, in which the varying air velocity in the venturi alters the fuel flow; this architecture is employed in most carburetors fou nd on cars. or Variable-venturi, in which the fuel jet ope ning is varied by t he slide (which simultaneously alters air flow). In "constant depression" carburetors, t his is done by a vacuum operated p iston connected to a tapered needle which slides inside the fuel jet. Throttle valve is a valve that regulates the supply of fuel to t he engine, To ensure a ready mixture, the carburetor has a "float chamber" (or "bowl") that contains a quantity of fuel at near-atmosp heric pressure, ready for use. This reservoir is constantly replenished with fuel supplied by a fuel pump. The correct fuel level in the bowl is maintained by means of a float controlling an inlet valve, in a manner very similar to that employed in a cistern (e.g. a toilet tank
To provide the extra fuel, a choke is typically used; this is a device that restricts the flow of air at the entrance to the carburetor, before t he venturi. Air correction jet : As the airflow through an "open venturi" (Solex type) carburetor rises, increasing vacuum starts to draw too muc h fuel through the main jet, so it starts to run rich at high air flows. To compensate for this, an air correction jet is inserted in the fuel delivery circuit after the main jet, which starts to add air to the fuel emulsion as the airflow increases. A pilot air jet is a small part of a carburetor. A carburetor is a device in the combustion engine of a vehicle. It mixes fuel and air before it can be converted into mechanical energy. The exact location of the pilot air jet varies depending on the type and model of the carburetor. Its special function contributes to the carburetor`s objective of creating an ideal airto-fuel ratio for smooth engine operation.
is a impossible to make the engine idle with any adjustment because the air draft in the carburetor at low idle is too weak to lift the fuel from the jet to the throttle. If it were only necessary for the suction to draw fuel through the jet opening, (J) the mixture proportion would be uniform at all speeds; but the def iciency below 16 m.p.h. is due to the fact that some of the suction force must be exerted in raising the fuel from the level in the float chamber up to the jet outlet: to avoid overflow with the engine not running , the jet must necessarily stand a safe distance above the float level. Air Bleed
IDLE PORT : The amount of fuel is adjusted by the mixture adjustment screw at the idle port.
