The valve guides are also made of cast iron and are pressed into the cylinder head with an interference fit. On the outer surface of the guide bushings there is a groove where the retaining ring is inserted. It ensures the accuracy of the position of the bushings when they are pressed into the cylinder head and protects the bushings from possible falling out.
The holes in the bushings are processed after pressing them into the block head. This provides a tight tolerance for the bore diameter and the accuracy of its location in relation to the seat and valve facets. The bores of the guide bushings have spiral grooves for lubrication. The inlet valve bushings are grooved up to half the bore length, while the exhaust valve bushings are grooved along the entire length of the bore.
On top of the guide bushings, oil-slinger caps made of heat-oil-resistant rubber with a steel reinforcing ring are put on. The caps encircle the valve stem and serve to reduce the penetration of oil into the combustion chamber through the gaps between the guide sleeve and the stem.
The valves are driven by a camshaft rotating in a bearing housing through intermediate levers. The gap between the camshaft cams and the lever is set by an adjusting bolt, on the spherical head of which the lever swings. The bolt is held against self-loosening by a lock nut.
Valves have two cylindrical springs - external and internal, sandwiched between the plate (up) and two support washers (at the bottom). The plate of springs is held on the valve stem by two crackers, which, when folded, have the shape of a truncated cone. Each lever is pressed against the end of the valve with a special (hairpin) spring.
To increase the wear resistance of the rod, both valves are nitrided, and the ends of the rods, on which the levers rest, are hardened by high frequency current.
The camshaft is cast, cast iron, the same for all engine models. Relies on 5 necks and rotates in an aluminum bearing housing mounted on the cylinder head. A driven sprocket is attached to the front end of the camshaft. From axial movements, the camshaft is held by a thrust flange placed in the groove of the front bearing journal of the shaft.
The camshaft is driven by a two-row roller chain from the crankshaft drive sprocket. The same chain drives the auxiliary drive shaft. The chain drive has a semi-automatic tensioner with a shoe and a chain guide with plastic lining. A restrictive pin is installed at the bottom of the cylinder block to prevent the chain from falling into the crankcase when removed (by car) camshaft sprockets.
For the correct relative position of the stars, i.e. for setting the valve timing, there are upper and lower installation marks. The upper marks are located on the camshaft sprocket and the bearing housing, the lower marks are on the crankshaft sprocket and the camshaft drive cover.