10.3.3.1. Conrod and piston group

Pistons. Diameter of pistons of various classes measured in the plane, a perpendicular axis of a finger at distance of 55 mm from the bottom of the piston, mm:
class A...... 81,965–81,975
class B...... 81,975–81,985
class C...... 81,985–81,995
class D...... 81,995–82,005
class E...... 82,005–82,015

Fig. 10-24. Marking of the piston and rod: 1 — an arrow for orientation of the piston in the cylinder; 2 — the repair size; 3 — a piston class; 4 — an opening class for a piston finger; 5 — a rod class on an opening for a piston finger; 6 — number of the cylinder

Under a piston finger pistons are sorted by diameter of an opening on three classes through 0,004 mm, as well as on other engines VAZ. Classes of diameters of the piston and an opening under a piston finger are branded on the bottom of the piston (fig. 10-24).
At production the mass of pistons is strictly maintained. Therefore at assembly of the engine it is not required to select pistons of one group on weight.
On the bottoms of repair pistons marking in the form of a triangle or a square is put. The triangle corresponds to increase in outer diameter by 0,4 mm, and a square — on 0,8 mm.
The arrow on the bottom of the piston shows how it is correct to focus the piston at its installation in the cylinder. It has to be directed towards the camshaft drive.
The piston finger of floating type, i.e. freely rotates in lugs of the piston and the plug of a rod. The finger is fixed in the piston by two steel lock rings.
Rod. In the top head of a rod the stalebronzovy plug is pressed. On diameter of an opening of this plug rods are subdivided into three classes through 0,004 mm (as well as pistons). Number of the 5th class is branded on the top head of a rod.

Fig. 10-25. Places on which it is allowed to delete metal at adjustment of mass of the top and lower heads of a rod

On the mass of the top and lower heads rods are subdivided into the classes (tab. 10-3) marked by paint on a rod core. On the engine rods of one class on weight have to be established. It is possible to adjust the mass of rods removal of metal from lugs on heads to the minimum sizes 16,5 and 35,5 of mm (fig. 10-25).

Classes of rods on the mass of the top and lower heads Table 10-3
Mass of heads of a rod,
Class
Color of marking
top
lower

519±3
A
white
186±2
525±3
B
blue

531±3
With
red

519±3
D
black
190±2
525±3
E
violet

531±3
F
green

519±3
G
yellow
194±2
525±3
H
brown

531±3
I
orange

Conrod bolts are pressed in a rod. When dismantling the engine to vypressovat bolts from rods it is not allowed.