The design of the cylinder head is shown in Figure 6.3. The nominal height of the engine cylinder head is factory-set and cannot be changed.
Allowable warpage (non-flatness) the mating surface of the head with the cylinder block in all directions, no more than 0.03 mm.
Attention! Cylinder head machining and seat lapping are not permitted.
Inner diameter of guide bushing (nominal):
- inlet valve - 6.0+0,015 mm;
- exhaust valve - 6.0+0,015+0,030 mm.
The camshaft bearing diameter is 23.0 mm.
Thrust bearing width – 18.85–0,08 mm.
The angle of the working chamfer of the valve seat is 45°.
Width of the working chamfer of the valve seat:
- inlet valve - 1.45 mm;
- exhaust valve - 1.45 mm.
The cylinder head is checked for leaks using a set of devices, by immersing the head in a bath of water, at a test pressure of 4.5 bar (4.5 kgf/cm²) and is controlled by the appearance of air bubbles.
Cylinder head gasket
Cylinder head gasket (1, Fig. 6.3) designed to seal the joint between the engine cylinder head and block, made of synthetic materials (asbestos-free) with metal edging of the holes for the cylinders.
The gasket is installed with the "Oben" mark ("Top") towards the cylinder head. The thickness of the gasket is determined by the maximum value of the piston protrusion from the cylinder block. If the piston bottom protrusion is 0.92–1.03 mm, install a gasket with 2 holes. If the protrusion is greater (1.03 mm), install a gasket with 3 holes.
(The original version is on the portal BMWMAN.ru)