GM 364702 F, Pistn Ay

Before installing the piston and connecting rod assemblies, ensure the cylinder walls are clean, the top edge of each cylinder is chamfered, and the crankshaft is in place. Remove the connecting rod cap from the number one connecting rod, take out the old bearing inserts, and wipe the bearing surfaces with a clean, lint-free cloth. Clean the back side of the new upper bearing half and lay it in place in the connecting rod, ensuring the tab fits into the recess without hammering or nicking the bearing face, and do not lubricate at this time. Clean the back side of the other bearing insert and install it in the rod cap, again ensuring the tab fits into the recess without applying lubricant. Position the piston ring gaps appropriately and slip a section of plastic or rubber hose over the connecting rod cap bolts. Lubricate the piston and rings with clean engine oil, attach a piston ring compressor, and leave the skirt protruding about 1/4-inch to guide the piston into the cylinder. Rotate the crankshaft until the number one connecting rod journal is at bottom dead center, then apply a uniform coat of engine oil to the cylinder walls. With the notch on top of the piston facing the front of the engine, gently place the piston/connecting rod assembly into the number one cylinder bore, resting the bottom edge of the ring compressor on the engine block, and tap the top edge to ensure contact around the circumference. Clean the number one connecting rod journal on the crankshaft and the bearing faces in the rod. Carefully tap the top of the piston with a wooden hammer handle while guiding the connecting rod into place on the crankshaft journal, ensuring the rings remain compressed and stopping if any resistance is felt. After installation, check the connecting rod bearing oil clearance before permanently bolting the rod cap in place by laying a piece of Plastigage on the number one connecting rod journal. Clean the connecting rod cap bearing face, install the rod cap ensuring the mating marks align, and tighten the nuts to the specified torque without rotating the crankshaft. Remove the rod cap carefully to avoid disturbing the Plastigage, compare the width of the crushed Plastigage to the scale on the container to obtain the oil clearance, and ensure it meets specifications. Scrape off any Plastigage material without scratching the bearing, clean the bearing faces, and apply a uniform layer of moly-based grease or engine assembly lube. Slide the connecting rod back into place, remove the protective hoses, install the rod cap, and tighten the nuts to the specified torque. Repeat the procedure for the remaining piston/connecting rod assemblies, ensuring cleanliness and correct piston orientation. After all assemblies are installed, rotate the crankshaft by hand to check for binding, and finally, check the connecting rod endplay against specifications to ensure correctness.

Prior to removing the piston and connecting rod assemblies, position the engine upright. Use a ridge reamer to completely eliminate the ridge at the top of each cylinder, following the manufacturer's instructions, as failing to do so may result in piston breakage. Once all cylinder wear ridges are removed, turn the engine upside-down. Before removing the connecting rods, check the endplay by mounting a dial indicator aligned with the crankshaft and touching the side of the number one cylinder connecting rod cap. Push the connecting rod forward to zero the dial indicator, then push it to the rear and note the reading; this distance indicates the endplay, which should not exceed the service limit, necessitating a new connecting rod if it does. Alternatively, use feeler gauges between the connecting rod and crankshaft throw to measure endplay. Check for identification marks on the connecting rods and caps, marking them if necessary. Loosen each connecting rod cap nut about half a turn, then remove the number one connecting rod cap and bearing insert without dropping the insert. To protect the crankshaft journal and cylinder wall, slip a short length of plastic or rubber hose over each connecting rod cap bolt before pushing the connecting rod/piston assembly out through the top of the engine, using a wooden tool to push on the upper bearing insert. If resistance is encountered, ensure all ridge material has been removed. Repeat this process for the remaining cylinders, and after removal, reassemble the connecting rod caps and bearing inserts in their respective rods, installing the cap nuts finger tight to prevent accidental damage to the bearing surfaces.