Maintenance of the Solex 32/32 DIDTA carburetor (BMW 5 Series E12)

Operating principle of the automatic starting device

The operating principle of the automatic starting device is based on the supply of current to the screen 64 (see figure "Main parts of the Solex 32/32 DIDTA carburetor",) a bimetallic spring which, as it heats up, acts on the lever 61 connected by the adjustable rod 42 to the drive of the throttle valve of the 1st chamber, and also on the use of the heat of the coolant circulating through the tubes in the liquid chamber 66. A sealing gasket 65 is installed between the liquid chamber and the housing of the bimetallic spring. In addition, for a short time, current is supplied to the bimetallic spring installed in the housing 46, which ensures the supply of additional air to accelerate the flow of the working mixture.

When the engine is started, voltage is applied to both bimetallic springs and the engine operates at an increased crankshaft speed. After a short period of time, the supply of additional air is cut off. The engine speed decreases, but the working mixture remains rich due to the fact that the air damper is held in the initial position by the bimetallic spring of the automatic starting device, which remains under voltage.

When the coolant temperature reaches 80-90°C, the power supply circuit of the bimetallic spring is broken by a thermoelectric sensor and the temperature of the spring is subsequently maintained only by the circulation of the coolant.

Adjusting the carburetor starting clearances

With the carburetor removed from the vehicle, open the throttle valve of the 1st chamber by pressing the levers 6 of its control, and completely close the air damper installed in the 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, acting through rod 43 and resting on lever 6 of the throttle valve control of the 1st chamber, slightly opens the throttle valve of the 1st chamber. Check the starting clearances of the air valve and the throttle valve of the 1st chamber, which should be within 3.2±0.15 and 0.8±0.05 mm, respectively.

If necessary, set the required starting clearances of the dampers by changing the length of the connecting rod 42, rotating the nut 44 in the connection "D".

Adjusting engine idle speed

Connect the tachometer and gas analyzer in accordance with the manufacturers' instructions, connect the vacuum gauge to the vacuum take-off nipple for the vacuum advance regulator.

Screw in adjusting screw 14 for supplying additional air at idle speed until it stops.

Using the mixture quantity adjusting screw, set the crankshaft speed within 700-750 rpm. The vacuum should be 1-15 mm Hg.

Using the mixture quality (composition) adjusting screw 40, achieve the highest and most stable engine crankshaft speed at idle.

Increase the engine speed to 860-900 rpm by turning screw 14 for supplying additional air at idle speed.

Using the mixture quality (composition) adjusting screw 40, achieve the highest and most stable engine crankshaft speed at idle.

Measure the carbon monoxide (CO) content in the exhaust gases. Turn the mixture quality (composition) adjusting screw so that the CO content becomes 1.5%. In this case, the crankshaft speed at idle will be 800±100 rpm.

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