The gas distribution mechanism needs periodic adjustment of the gaps between the rocker arms and valves, which should be performed on a cold engine after a run of 16,000 km
Or when there are signs of clearance violations (valve knock, engine power reduction, flashes in the carburetor, "shots" in the muffler) in the following order:
- remove the tube of the vacuum regulator;
- carefully remove the rocker cover, avoiding damage to its gasket;
- install the piston of the first cylinder according to mark 2 (Fig. 4) on the crankshaft pulley in the TDC. during the compression stroke and with a feeler gauge, check the clearance between the rocker arms and the valves of the first cylinder.
If the gap is incorrect, unscrew the lock nut 5 (Fig. 5) of the adjusting screw 4 and, turning the adjusting screw with a screwdriver, set the gap on the probe, then, holding the adjusting screw with a screwdriver, tighten the lock nut and check again the correctness of the set gaps;
- after adjusting the clearances of the next cylinder, turn the crankshaft half a turn and adjust the clearances for the remaining cylinders according to the order of their operation: 1–2–4–3.
Clearance between rocker arms and valves on a cold engine (at 15-20°):
For exhaust valves of the 1st and 4th cylinders, mm ─ 0.30 - 0.35
For other valves, mm ─ 0.35 ─ 0.40