Adjusting Pierburg/Solex 1B3 Carburetor

PROCEDURE

Carburetor 1B3 Parts 1 – heating element; 2 – carburetor body; 3 – O-ring; 4 – mixture quality adjustment screw; 5 – solenoid valve; 6 – power enrichment economizer; 7 – mixture quantity adjustment screw; 8 – accelerator pump; 9 – valve seat; 10 – spring; 11 – pump piston cup; 12 – accelerator pump piston; 13 – piston guide; 14 – gasket; 15 – float pivot pin; 16 – float; 17 – main fuel jet; 18 – carburetor cover; 19 – economizer fuel jet; 20 – idle fuel jet; 21 – choke pneumatic actuator; 22 – needle valve; 23 – automatic choke; 24 – gasket; 25 – cover; 26 – accelerator pump nozzle; 27 – spring; 28 – nozzle ball valve; A – choke valve starting clearance

Checking Fuel Level in Float Chamber. Float position is not adjustable. If a fault is found, check the float for leaks and the condition of the needle valve. Replace faulty parts.

Adjusting Engine Starting Idle Speed 1 – throttle valve stop screw; 2 – throttle lever

PROCEDURE 1. Start and warm up the engine. 2. Connect a diagnostic tachometer to the engine. 3. Stop the engine. 4. Turn lever 2 so that the throttle valve is fully open. 5. Start the engine without pressing the accelerator pedal. 6. Check engine speed, which should be within 2000±100 min-1. 7. If necessary, adjust the speed by turning screw 1.

Adjusting Throttle Valve Opening 1 – throttle valve stop screw; 2 – throttle valve limiting lever

The throttle valve position is set at the factory and does not require adjustment during operation. However, if the adjustment has been disturbed, it can be restored as follows: PROCEDURE 1. Remove the plug from screw 1. 2. Turn throttle lever 2 (see Figure Adjusting Engine Starting Idle Speed) so that it does not touch stop screw 1. 3. Unscrew screw 1 so that it does not touch lever 2. 4. Screw in screw 1 until it contacts lever 2. 5. Turn screw 1 further by a quarter turn (90°). 6. Install a new plug on screw 1.

Adjusting Accelerator Pump 1 – accelerator pump drive cam; 2 – locking screw

PROCEDURE 1. Remove the carburetor. 2. Remove the carburetor cover, fill the float chamber with fuel, and install the carburetor cover. 3. Place a graduated measuring cylinder with a funnel under the carburetor. 4. Move lever 2 (see Figure Adjusting Engine Starting Idle Speed) away from screw 1. 5. Slowly turn the throttle valve from stop to stop 10 times, taking about 3 s per stroke, to actuate the accelerator pump. 6. Measure the fuel quantity in the cylinder and divide by 10. This gives the fuel quantity delivered by the accelerator pump per cycle. This value should be 1.0±0.15 cm3. 7. If necessary, adjust the accelerator pump output by turning cam 1 after loosening screw 2. Turning the cam toward "+" increases output; toward "-" decreases it. After adjustment, tighten screw 2 and secure it with paint.

Adjusting Idle Speed. Adjustment is performed on a warmed-up engine, with valve clearances adjusted and ignition timing set correctly, in the following order: PROCEDURE 1. Switch off all electrical consumers (radio, headlights, etc.). 2. Disconnect the crankcase ventilation hose from the air cleaner and plug it. 3. Connect a diagnostic tachometer and gas analyzer.

4. Using the mixture quantity adjustment screw (indicated by arrow), set the crankshaft speed within 800±50 min-1.

5. Using the mixture quality adjustment screw (indicated by arrow), set the carbon monoxide (CO) content in the exhaust gas to no more than 2±5%. 6. Check and, if necessary, restore the idle speed. Check and, if necessary, restore the CO content in the exhaust gas.