Adjusting and checking the carburetor (Mercedes-Benz E-Class W123)

Checking and setting the level in the float chamber

1. Remove the carburetor.

2. Remove the solenoid valve.

3. Remove the float chamber, jet and spring.

4. Turn the carburetor over and measure the distance between the highest point of the float and the plane of the float chamber, which should be 17±0.5 mm.

5. If necessary, adjust the size by bending the float lever.

6. Install the float chamber, jet and spring.

7. Install the solenoid valve.

8. Install the carburetor.

Checking the dosing needle

The needle moves freely in the holder and must therefore be in a strictly defined position. Its surface is machined with high precision, and the slightest wear worsens the dosage and atomization of the fuel; it should not have any smoothed areas. The holder is secured with a conical screw adjacent to the chamfer. The plastic washer should be in the same plane as the lower part of the piston.

Checking the diaphragm

The diaphragm must be intact, without damage, and properly fit the support surfaces, and the mounting grooves must fit the support projections. Check the position of the mounting groove.

Adjusting the throttle valve starting clearance

1. Without disconnecting the engine cooling system hoses, unscrew the three screws securing the thermostat and remove it from the carburetor.

2. Remove the throttle return damper.

3. Loosen the mixture quantity adjusting screw until the throttle valve is completely closed.

4. Disconnect the throttle valve opening lever.

5. Apply marks to the throttle valve angular position.

6. Tighten the mixture quantity adjusting screw until the throttle opening angle reaches 6°.



7. Install the lever.

8. Open the throttle valve as far as possible using the lever.

9. Release the lever and check the throttle position, which should be 16°±1 or 0.65±0.05 mm.

10. If there is any deviation from the norm, adjust the lever.

11. Install and adjust the throttle return damper.

12. Install the thermostat, observing its adjustment.

Adjusting the throttle damper

1. Start the engine at idle speed, disconnect the vacuum hose and use the starting device adjusting screw to set the engine speed to 1200-1400 rpm.

2. Connect the vacuum hose.

3. Check the clearance between the adjusting screw and the throttle control lever, which should be 0.5 mm.

Vacuum hose connection diagram on a Stromberg carburetor

Adjusting the thermostat

1. Clamp the heating hoses and disconnect them from the thermostat.



2. Disconnect the connector and remove the thermostat assembly.

3. Heat the thermostat cover to a temperature of 20°C.

4. Install the cover with gasket on the starting device housing.

5. Turn the cover clockwise until the lever is in the middle of the 2nd profile of the throttle opening sector.

6. Apply marks of mutual arrangement on the cover and on the body of the starting device. Remove old marks if necessary.

7. Install the thermostat.

8. Attach the shoe.

9. Connect the heating hoses and bleed air from the engine cooling system.

Adjusting the quality (composition) of the mixture at fast idle

1. Warm up the engine.

2. Remove the protective cover of the trigger box of the starting device.

3. Open the throttle valve slightly and set the piston control lever to the 2nd sector profile at the level of the throttle control lever.

4. Start the engine.

5. Use the additional air adjusting screw to achieve the specified carbon monoxide (CO) content in the exhaust gases.

Adjusting engine idle speed and carbon monoxide (CO) content in exhaust gases

1. Warm up the engine.

2. Make sure that the throttle valve does not hit the return damper or the fast idle control lever at idle speed.

3. Use the adjusting screw on the control lever to achieve normal crankshaft speed at idle.

4. Check and, if necessary, adjust the carbon monoxide (CO) content in the exhaust gases. To do this, remove the plug from the electromagnetic valve and unscrew it to increase the CO content and vice versa.