Warping of the mating plane of the head with the cylinder block, not more than, mm: 0.1.
Permissible height of the cylinder head after grinding, not less than, mm: 132.60.
Cylinder head gasket
The cylinder head gasket is labeled «oben» (top). The plane with this label at assembly should be turned towards a head of cylinders.
Valve seats
The valve seats are made from powder metallurgy steel and are non-replaceable. If traces of burning or wear are found that cannot be removed by grinding, the cylinder head as a whole is replaced.
Valve seat specifications
* In parentheses is the value for the engines of the model «DS» from September 1985 and models «NP»
Valve guides
The valve guides are made of special brass and are pressed into the cylinder head.
Maximum allowable limit clearance (when worn), between the valve stem and the guide sleeve, mm:
- for inlet valves: 1.0;
- for exhaust valves: 1.3.
Hole diameter in valve guide bushings, mm 8.013-8.0.35.
Valves
The valves are located in the head parallel in one row above the cylinders vertically and are actuated directly by the camshaft cams through the pushers (model engines «DR») or via hydraulic pushers (engines «DS» or «NP»). Exhaust valves are not subject to grinding.
Valve characteristics
* Values in parentheses are for the engine of the model «NP».
Clearances in the valve drive mechanism
Model engines «DR» And «DS» (until September 1985)
The gap between the camshaft cams and shims at a coolant temperature above 35°C should be 0.25±0.05 mm for intake valves and 0.45±0.05 for exhaust valves, on a cold engine, respectively 0.20±0.05 and 0.40±0.05 mm.
The gap is adjusted by selecting the thickness of the shims mounted on the upper ends of the pushers.
Spare parts are supplied with shims with a thickness of 3.00 to 4.25 mm at intervals of every 0.05 mm.
Model engines «DS» (since September 1985) And «NP»
The clearances in the valve drive mechanism are adjusted automatically by hydraulic tappets.
Valve springs
Each intake and exhaust valve has two springs. The springs are the same for both intake and exhaust valves.
Pushers
The valve lifters are located directly in the cylinder head. On the upper ends of the pushers of the engines of the model «DR» And «DS» (until September 1985) adjusting washers of various thicknesses are installed to adjust the thermal clearances of the valves.
Visitor comments