GMC 12514101 Piston Kit,(W/Pinion & Rings)(Std)

Prior to fitting of the piston and connecting rod assemblies the cylinder walls should be clean, the top edge of each cylinder should be chamfered and the crank shaft should be fitted. Take off the connecting rod cap of the number one connecting rod and pull out the bearing inserts; there are always some debris on the bearing surface-wipe this area with a clean cloth. Remove any dirt or grease from the back side of new upper bearing half, place the half in its place on the connecting rod so that the tab should fit into the recess and so that you do not hammer the bearing face or nick it, do not lubricate at this time. Remove the bearings on one rod cap and clean the other side of the bearing insert that is on the other rod cap and then you will place the other bearing insert into the rod cap making sure the tab gets into the recess without use of grease.-align the gaps of the piston ring in the right position and place a section of a plastic or rubber hose over the connecting rod cap bolts. Dip the piston and the rings in clean engine oil, place the piston ring compressor on it and center the skirt about 1/4-inch away. Turn the crankshaft through 720 degrees and place the number one connecting rod journal at bottom dead centre and wipe the cylinder walls with engine oil. With your notch on top of the piston facing the front of the engine, carefully install the piston and connecting rod assembly into the number one cylinder bore with bottom of ring compressor lying on the block and tap the top side for better contact. Scrape, deglaze and clean the 'top' of the number one connecting rod journal, on the crankshaft, and the bearing surfaces, in the rod. Ease the piston onto the crankshaft journal with downward pressure on the ring compressor to avoid the piston rings' shooting out through the open upper end of the cylinder; with a wooden hammer handle, gently knock the top of the piston. After the fixture is set, measure the oil clearance of connecting rod bearing by placing a piece of Plastigage at number one connecting rod journal before finally tightening the rod cap permanently in place. Scrub the connecting rod cap bearing face, Remove protectors from the connecting rod bolts and then carefully fit the rod cap in a manner that the marks faced each other. All the nuts to be tightened performed in three steps without having to rotate the crankshaft. Slowly and cautiously undo the rod cap to avoid upsetting the Plastigage and by referring to the width of the crushed Plastigage on the scale on the container get the oil clearance that should conform to the specifications. Remove as much Plastigage material from the bearing without damaging the bearing itself, clean both bearing faces, using a finger or paper towel applied a thin film of clean engine assembly lube. Put the connecting rod back to its position, take off the protective hoses, fix the rod cap and tighten the nuts in three sequences. Do the same for the piston and connecting rod assemblies that are yet to be cleaned; also make sure that the pistons are in the right position. Once all the assemblies are in place take the crank by the aid of a breaker bar, turn the crankshaft to feel for binding, and at last check the connecting rod end float, match them up to the standard provided for correctness.

If they are not marked, use a small center punch to create indentations for identification.

Check the connecting rod bearing oil clearance before permanently bolting the rod cap in place.

A new connecting rod is necessary.

Afterward, scrape off all Plastigage material from the rod journal and bearing face without causing any damage, ensuring the bearing faces are impeccably clean.

If the cylinder block requires any machine work, including finish honing, it is advisable to have the pistons available for checking piston-to-bore clearance, which is a critical measurement best left to the machine shop.

Turn the engine so the piston is at the bottom of its stroke.

After removal, reassemble the connecting rod caps and bearing inserts in their respective connecting rods and install the cap nuts finger-tight. Leaving the old bearing inserts in place until reassembly will help prevent the connecting rod bearing surfaces from being accidentally nicked or gouged.

Before installation, ensure that the cylinder walls are clean, the top edge of each cylinder is chamfered, and the crankshaft is in place.

Turn the engine upside-down.

A piston ring groove-cleaning tool should be used to remove carbon deposits from the ring grooves. Alternatively, a piece of broken old ring can be used, taking care not to remove any metal or damage the grooves.

Clean the number one connecting rod journal on the crankshaft and the bearing faces in the rod.