Photo 14.1A. Pierburg carburetor - top view:1. Steam separator; 2. Choke cover; 3. Lowering block (discoveries) air damper; 4. Fuel hose; 5. Vacuum switch; 6. Vacuum block of the secondary throttle body.
Photo 14.1B. Pierburg carburetor - view from the choke cover.
Photo 14.1C. Pierburg carburetor - view from the accelerator pump (1) and lowering block (discoveries) air damper (2).
Photo 14.1D. Pierburg carburetor - view from the enrichment valve side at partial loads (1) and accelerator pump cam (2).
2. Automatic suction is a conventional type and is controlled by a bimetallic spring. The choke cover is heated by electric current and coolant, which ensures a quick response to changes in engine and outside air temperature. Excessive suction is eliminated due to the eccentric placement of the air damper, the vacuum system for lowering the damper and the connection of the air damper with the throttle mechanism.
3. With the engine at normal operating temperature, the idle mixture is supplied through the bypass system. Although some illustrations show an idle shut-off valve, all the carburetors we examined did not have such a valve, and the idle speed was adjusted at the throttle stop screw.
4. The throttle valves open sequentially. The primary throttle valve opens mechanically and the secondary throttle valve opens due to vacuum developing in both air throats, but the secondary throttle valve cannot open until the primary throttle valve is at least half open. For safety reasons, both throttle valves are closed mechanically.
5. Efficient engine operation at all speeds and loads is ensured by the partial load enrichment valve and the primary and secondary transition systems. The accelerator pump provides the extra fuel needed for fast acceleration.
Pic. 3.40. Pierburg carburetor: accelerator pump parts: 1.Primary throttle valve; 2. Primary pre-spray; 3. Cam; 4. Pump inlet valve; 5. Spring; 6. Membrane; 7. Pump lever; 8. Plunger; 9. Cover; 10. Return jet; 11. Exhaust valve; 12. Injector tube.
Pic. 3.41. Pierburg carburetor: throttle valve actuator: 1. Primary throttle valve; 2. Secondary throttle valve; 3. Throttle valve stop screw; 4. Segment lever; 5. Throttle lever; 6. Fast idle speed adjustment screw; 7. Secondary locking lever; 8. Mounting bracket; 9. Vacuum block; 10. Spring; 11. Fork lever; 12. Secondary thrust screw.
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