Pistons
Pistons with a steel thermoregulating ring, with continuous skirts are made of aluminum alloy with lead coating.
Piston weight, g: 364.
Clearance between the piston and the cylinder, measured along the bottom of the skirt, not more than, mm: 0.01.
Groove depth, mm:
- for compression rings: 3.63-3.75;
- for the oil scraper ring: 4.23-4.35.
The dimensions of the piston and cylinder groups must be selected in strict accordance with the table below.
Size groups of cylinders and pistons
*Piston diameter must be 0.01 mm smaller
Displacement of the axis of the hole for the piston pin relative to the diametral plane of the piston, mm: 0.8.
Piston pins
Piston pins are made of heat-treated steel. The pin is pressed with an interference fit into the upper head of the connecting rod, which is preheated to a temperature of 280°C, and rotates freely in the piston bosses.
Piston pin outer diameter, mm: 20.
Piston pin length, mm: 65.
Gap between piston pin and piston, mm: 0.0015-0.0195.
Piston rings
Three rings are installed on each piston: two compression and one oil scraper.
Gap in the lock, mm:
- upper and lower compression rings: 0.30-0.45;
- oil scraper ring: 0.40-1.40.
Connecting rods
Connecting rod steel, forged, with an I-section rod. In terms of mass, connecting rods without pistons and connecting rod bearing shells of one engine should not differ from each other by more than 8 g.
The distance between the axes of the connecting rod heads, mm: 122.
Axial clearance of connecting rods on the crankshaft journals, not more than, mm: 0.11-0.24.
Connecting rod bearing shells
Connecting rod bearing shells are trimetallic. The backing of the liners is made of steel tape.
Width of connecting rod bearing shells, mm: 19.0.
Gap between liners and connecting rod journals, mm: 0.02-0.06.
Spare parts are supplied with liners of two repair sizes: thickness increased by 0.25 mm (label «A») and 0.50 mm (label «IN»).
Crankshaft Dimensions
Camshaft journal dimensions and bearing bushing bore diameters
Connecting rod marking depending on the mass
Crankshaft
The crankshaft is steel, forged, with three bearings. The shaft journals are hardened in an induction furnace.
The ovality of the surfaces of the main and connecting rod journals, no more than, mm: 0.006.
The taper of the surfaces of the main and connecting rod journals, not more than, mm: 0.01.
Permissible runout of the middle main neck when resting on the extreme main necks, no more than, mm: 0.03.
Permissible deviation from parallelism between connecting rod and main journals, no more than, mm: 0.012.
Permissible runout of the crankshaft flange, no more than, mm: 0.015.
Axial clearance of the crankshaft, measured on the middle support, mm: 0.09-0.20.
Gap between liners and main journals of the crankshaft, not more than, mm:
- 1st root neck: 0.020-0.046,
- 2nd root neck: 0.010-0.036;
- 3rd root neck: 0-0.0315.
Width of supports, mm.
- 1st support: 25.00;
- 2nd support: 29.00;
- 3rd support: 22.00.
Main bearing shells
Inserts of radical bearings trimetallic. The backing of the liners is made of steel tape.
Upper liners nominal and repair (enlarged by 0.25 and 0.50 mm) sizes have green labels, and the bottom ones are brown. Repair liners are made of increased thickness for crankshaft journals reduced by 0.25 and 0.50 mm. These inserts, in addition to the color label, have a corresponding alphanumeric code.
Marking of liners of main bearings
Flywheel
The flywheel is cast iron, attached to the rear end of the crankshaft with six bolts.
Flywheel diameter, mm: 248.
The maximum allowable runout of the flywheel, measured on the gear rim, mm: 0.5.
The maximum thickness of the metal layer removed when grinding the flywheel surface under the clutch disc, mm: 0.3.
The size between the bearing surface of the clutch cover and the contact plane of the driven disk, mm: 5.1±0.1.
The number of teeth of the gear rim is 122.
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