The thermal gap between the valves and rocker arms is adjusted when repairing the cylinder head
Also when there is a knocking sound in the area of the valve cover
With an increased gap, a characteristic loud knock appears.
If the gap between the valves and rocker arms is small, the engine will be “squeezed”, or they say “stupid.”
This will reduce its power and throttle response, and increase wear on the valve mechanism.
Adjustment is carried out on a cold engine.
Remove the carburetor air filter housing to do this:
Use a screwdriver to loosen the clamp and remove the crankcase gas exhaust hose.
Snap off the five clips, remove the cover of the air filter housing, and take out the filter element.
Use a screwdriver to loosen the clamp and remove the corrugated air intake hose.
Use a screwdriver to bend the antennae of the lock washers, and use a 10mm wrench to unscrew the three nuts
Remove the air filter housing
Disconnect the crankcase gas exhaust pipe
Disconnect the hose of the vacuum regulator of the ignition sensor-distributor
Use a 10mm socket wrench to remove the six bolts of the cylinder head cover
Remove the cover
Remove the sealing gasket.
Install the piston of the first cylinder to TDC.
To do this, turn the crankshaft so that the third mark on the pulley aligns with the boss on the camshaft sprocket cover.
After this, remove the distributor cap and check that the slider is in the contact position of the 1st cylinder.
Otherwise, turn the crankshaft one turn.
Both valves of the first cylinder must be closed. The rocker arms swing freely.
Using a 14mm wrench, loosen the locknut of the adjusting screw and unscrew the adjusting screw one or two turns.
Between the valve stem and the rocker arm in install the dipstick.
Turn the adjusting screw until the feeler gauge moves in the gap with little force.
Having set the gap, hold the adjusting screw and tighten the lock nut and check the gap again. We adjust the clearances of both valves of the first cylinder.
Then use a special key for the ratchet:
Rotate the crankshaft half a turn (180°) and adjust the clearances in the valve drive of the 2nd cylinder.
Rotate the crankshaft another half turn (180°) and adjust the clearances in the valve drive of the 4th cylinder.
Rotate the crankshaft another half turn (180°) and adjust the clearances in the valve drive of the 3rd cylinder.
The clearances in the valve mechanism should be 0.35–0.40 mm for the intake valves of the first and fourth cylinders (outer valves), and 0.40–0.45 for the others.
After adjusting the valves, you need to start the engine and after warming up, do a test drive.
Check engine operation in all modes. If the valve mechanism is not operating satisfactorily, repeat checking the clearances.