Carburetor K-131 (Fig. 1) - vertical, balanced, with falling flow, single-chamber, double-diffuser
Main dosing system - with pneumatic braking of fuel and emulsification in the well, with a central supply of air emulsification.
In addition, the carburetor has an autonomous idle system and a semi-automatic starting and warming up system.
Carburetor maintenance consists of periodically checking the reliability of fastening of the carburetor and its individual elements, checking and adjusting the fuel level in the float chamber, adjusting the low speed of the engine crankshaft in idle mode, checking the operation of the accelerator pump and economizer, cleaning, purging and flushing carburetor parts from tarry deposits, checking the flow rate of the jets.
Check the fuel level with the car engine not running and installed on a horizontal platform.
When pumping fuel using a manual pump drive, the fuel level in the carburetor float chamber must be established within the limits marked by the marks (tides) “a” (Fig. 2) on the walls of the inspection window.
If the level deviates from the specified limits, make an adjustment by removing the float chamber cover.
Adjust the level by bending tongue 3 (Fig. 3).
At the same time, by bending limiter 2, set the needle stroke 5 of the fuel supply valve to 1.2–1.5 mm.
After adjustment, check the fuel level again and, if necessary, adjust again.
Considering that during operation due to wear of the float mechanism the fuel level gradually increases, set it when adjusting to the lower limit.
In this case, the fuel level will remain within acceptable limits for a longer period of time.
When adjusting the fuel level in the carburetor float chamber, do not bend the float tongue by pressing the float, but bend it using a screwdriver or pliers.
Adjust the low crankshaft speed in idle mode on a warm engine with a working ignition system.
Make adjustments in the following order:
Preliminarily set the crankshaft rotation speed at idle speed with screw 2 (Fig. 4) to 550–600 min -1 .
Set screw 1 to the position that provides the highest engine speed at a given throttle position.
Screw 1 also regulates the “CO” content in the exhaust gases.
Finally set screw 2 to low idle speed (550–650 min -1).
Adjust valve drive 1 (Fig. 5) for unbalancing the float chamber with screw 3.
When the throttle valve is fully released, the valve should be open.
Check the operation of the accelerator pump if, when you sharply press the throttle pedal, dips in engine operation are observed and the engine slowly increases speed.
To check, sharply open the throttle valve, and fuel should flow from the accelerator pump nozzle.
On a special stand you can check the flow of the accelerator pump, which should be at least 8 cm 3 for 10 piston strokes.
During the operation of the carburetor, due to wear of the piston and the walls of the accelerator pump well, its supply may be insufficient.
To increase the flow, move limit washer 2 (Fig. 6) on the accelerator pump rod to the lower groove 3.
When operating a vehicle in high-temperature conditions, reduce the flow of the accelerator pump by moving the limit washer to the upper groove of rod 1.
If the engine does not produce maximum power at full throttle, check that the economizer is fully engaged.
To do this, check the gap between the bar and the nut of the economizer drive rod with the throttle valve fully open, which should be (3±0.2) mm (Fig. 7).
If necessary, adjust this gap using a nut, then secure the nut by crimping it along its small diameter.
The throughput of the jets is determined on a special stand by pouring water through them under the pressure (pressure) of a column of water with a height of 1000±2 mm and a temperature of (20±1) °C.
Nozzle throughput, ml/min:
- - main fuel jet 350±4.5
- - idle fuel jet 55±1.5
- - main air jet 175±4
- - idle air jet 290±7
When screwing in and out the jets, be careful not to damage the threads in the holes.
Keep in mind that the main fuel jet and idle fuel jet are similar in appearance, but have different threads.
Rinse carburetor parts with benzene or unleaded gasoline, then blow them with compressed air.
Do not use metal wire to clean jets and calibrated holes, as this will disrupt their dimensions and capacity.
If electronic unit 13 (see Fig. 1) or microswitch 12 fails along the way, connect carburetor fittings “a” and “b” with one of the hoses, bypassing the solenoid valve.