The A.60308 mandrel is a cylindrical rod with a diameter and length of the working part of 21 and 80 mm, respectively. The diameter of the centering shank, which enters the piston pin hole, is (14.9±0.05) mm.
If some parts of the connecting rod and piston group are not damaged and slightly worn, they can be used again. Therefore, when disassembling, they are marked so that later the group can be assembled with the same parts and installed in the previous engine cylinder.
Before assembly, select the pin to the piston. For correct mating, it is necessary that the piston pin, lubricated with engine oil, enters the piston hole with a simple press of the thumb and does not fall out of it if the piston with the piston pin is held in a vertical position. A pin that falls out is replaced with another one of the next category (see section. "Features of the device"). If the piston had a third category pin, then the piston with the piston pin is replaced.
Since the pin is inserted into the upper head of the connecting rod with tension, it is necessary to heat the connecting rod to expand the upper head. To do this, place the connecting rods in an electric furnace heated to 240°C for 15 minutes. For better heating, place the connecting rods with the upper heads inside the furnace.
The finger is prepared for assembly in advance by placing it on roller 1 (figure 44) device A.60325 and installing a 4 mm thick spacer ring with an outer diameter of 22 mm and an inner diameter of 15 mm between the finger and the handle. At the end of the device, install guide 2 and secure with screw 3. Tighten the screw loosely to prevent jamming when the finger expands from contact with the heated connecting rod.
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To properly connect the pin to the connecting rod, pressing must be done as quickly as possible, since the connecting rod cools quickly and after cooling it will not be possible to change the position of the pin. The piston with the connecting rod must be assembled so that the arrow on the piston bottom is directed towards the outlet of the oil hole on the lower head of the connecting rod (see figure 5).
The connecting rod, removed from the furnace, is quickly clamped in a vice. The piston is placed on the connecting rod, ensuring that the hole for the pin matches the hole in the upper head of the connecting rod. The piston pin, secured to the device, is pushed into the piston hole and into the upper head of the connecting rod (figure 45) until the shoulder of the device stops against the piston. During this operation, the piston should be pressed with its boss against the upper head of the connecting rod in the direction of pressing the pin (shown by the arrow in Figure 45). Then the finger will take the correct position.
After the connecting rod has cooled, lubricate the pin with motor oil through the holes in the piston bosses. Lubricate the grooves on the piston and the piston rings with motor oil and install the rings on the piston. Orient the piston rings so that the lock of the upper compression ring is at an angle of approximately 45° to the axis of the piston pin, the lock of the lower compression ring is at an angle of approximately 180° to the axis of the lock of the upper compression ring, and the lock of the low-removability ring is at an angle of approximately 90° to the axis of the lock of the upper compression ring.
The lower compression ring is installed with the notch facing down. If the ring is marked "Top" or "TOP", then the ring is installed with the notch facing up (to the piston bottom). Before installing the oil scraper ring, check that the joint of the spring expander is located on the side opposite the ring lock.