The total height of the cylinder head, mm: 135.63.
Permissible warping of the surface of the head mating with the cylinder block, no more than, mm: 0.025 (grinding of this surface is not allowed).
Cylinder head gasket
The cylinder head gasket is installed with a label «Oben» or «Thor» («Top») up without the use of sealant.
Valve seats
The valve seats are made of cast iron and are pressed into the cylinder head.
Seat angle: 44°40'.
Working chamfer width, mm:
- inlet valve seats: 1.0-1.4;
- exhaust valve seats: 1.4-1.8.
Gasket thickness after compression, mm: 1.15-1.30.
Valve guides
The valve guides are pressed into the cylinder head.
Guide bushing hole diameter, mm.
- nominal: 7,000-7,015;
- 1st repair size: 7.075-7.090;
- 2nd repair size; 7.150-7.165.
Gap between guide bushings and valve stems, mm
- inlet valves. 0.03-0.06;
- exhaust valves: 0.04-0.07.
The protrusion of the valve guide bushings relative to the plane of the cylinder head, mm: 10.7-11.0.
Valves
Each engine cylinder has two intake and exhaust valves. The inlet valves are made of special steel, the outlet valves are sodium cooled. The valves are installed in the cylinder head in a V-shape at an angle of 45°. Valve plates are locked with crackers. Valves do not have rotary devices.
Valve characteristics
Clearances in the valve drive mechanism
The use of hydraulic pushers eliminates the need to adjust the gaps between the hydraulic pusher and the camshaft cam.
Valve springs
Valve springs are the same for intake and exhaust valves.
Hydraulic valve lifters
The valves are actuated directly by the camshaft cams through hydraulic tappets that are installed between the cams and the ends of the valve stems. Hydraulic tappets select clearances in the valve actuation mechanism, so clearance adjustment is not required. The gaps between the camshaft cams and pushers on a running engine are zero.
The pressure of the oil supplied to the pushers is limited by a special valve installed in the cylinder head on the side of the ignition distributor.
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