Verification and replacement of pistons and connecting rods

■ Detach the piston from the connecting rod and mark together. The piston pin is held laterally by a spring ring. This ring can be removed with a small screwdriver, by undermining it in the place provided for it.

■ If the connecting rod shells rotate in the foot, the complete connecting rod must be replaced.

■ Determine the play in the crank shells, in the same way as for the main sockets, and choose new shells.

■ The clearance of the piston pin in the bushing should be within 0.01…0.016.Mm. If it's too big, the bushing can be replaced. The piston pin is not a spare part and if damaged, the complete piston must be replaced.

■ The connecting rods in the kits are selected by weight. with low tolerance. Therefore, many connecting rods are replaced, but the whole set.

■ For racing cars, the difference in connecting rod masses can be reduced to ± 1 g. Suitable places are provided in the head and foot for this purpose, which can be processed.

■ The piston and connecting rod should be in the position shown in the picture when assembled 3.13. Spring ring lock (piston pin protection) should be at the top, on the opposite side of the recess at the opening.

■ The diameter of the piston pin is 22,0 Mm. The axis of the pin is displaced by 1 mm from the axis of the piston.

■ The piston rings are wide 1,5; 2,0 and 3,9 Mm.

■ The play in the ring buckle is equal to when installed:

1. ring - 0.3…0,5 Mm,

2. ring 0.3…0,5 Mm,

3. ring - 0.25…0.5 Mm.

■ The operating clearance of the rings in the grooves is:

1. ring – 0.045…0,077 Mm,

2. ring - 0.020…0,072 Mm,

3. ring – 0,030…0.065 Mm.

■ The working clearance of the piston is 0.04…0,06 Mm. The difference in mass between the pistons may be ± 2,5 g.

■ For repair purposes, an oversized piston is provided with a diameter increased by 0.4 Mm.

■ The piston rings have the word TOP on the flat side, which must be visible from above after installation.

■ Use a clamp to install the pistons in the engine block.