Adjusting the Solex DIDTA 32/32 carburetor (BMW 3 Series E21)

Adjusting the carburetor starting clearances

With the carburetor removed, press control lever 6 to open the throttle valve of the 1st chamber and completely close the air damper installed in cover 52 of the carburetor.

Close the throttle valve of the 1st chamber and release the air valve, thereby bringing the starting device into working condition. The air valve is slightly open and sector 11, resting on the control lever 6 of the throttle valve of the 1st chamber, by means of rod 42 slightly opens the throttle valve of the 1st chamber. check the starting clearances (opening) air damper and throttle valve of the 1st chamber, which should be within 3.2±0.15 mm and 0.8±0.05 mm, respectively.

If there is a deviation from the norm, set the proper clearances by changing the length of connecting rod 42, turning the nut on the end with which it is attached to lever D.

Adjusting the fuel supply with the accelerator pump

Remove the carburetor.

Fill the carburetor float chamber with fuel through the vent hole and place a measuring cup with a funnel under the carburetor.

By pressing the throttle control lever of the 1st chamber approximately 10 times, activate the accelerator pump, while the fuel supply by the pump in one cycle should be 0.9+0.1 cm³.

If necessary, adjust the fuel supply from the accelerator pump by turning the nut on the end of the control rod or (depending on modification) by moving the pump drive cam lever, after first unscrewing the lower lever screw.

Adjusting the opening of the throttle valve of the 2nd chamber

The throttle valve of the 2nd chamber should open by 0.05 mm. Adjustment is made by turning the adjusting screw 1.

Rough adjustment of engine idle speed

Rough adjustment of the engine idle speed is performed only if it is impossible to correctly adjust the idle speed and the carbon monoxide (CO) content in the exhaust gases.

Turn idle speed adjustment screw 1 all the way in.

Using the adjusting screw of the throttle valve of the 1st chamber 3, set the engine crankshaft speed within 700-750 rpm.

Using the mixture quality (composition) adjustment screw, after removing the plug, achieve a CO content in the exhaust gases of approximately 2%.

Repeat the above operations until the proper idle speed is established with a CO content of 2% in the exhaust gases.

Adjusting engine idle speed

Use the idle speed adjusting screw 1 to set the rated engine crankshaft speed (see subsection "Detailed technical specifications").


Use the mixture quality (composition) adjustment screw 2 to achieve the specified CO content in the exhaust gases (see subsection "Detailed technical specifications").

Repeat the above operations until the engine idle speed and CO content in the exhaust gases are within the normal range.

After completing the adjustment, install a new plug into the hole for the mixture quality (composition) adjustment screw.



If the carburetor does not have an idle speed adjustment screw, the engine idle speed is adjusted using the throttle valve adjustment screw 3.