Chevrolet 12646457 Piston Kit

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Before removing the assemblies of the piston and the connecting rod, all the cylinder head and all pan must be taken off. Their upper extent is approximately 1/4 inch below the cylinder top where, checking with your fingernail, you should look for any ridge left by carbon or wear; if it exists, the piston should be run through a ridge reamer. Once the ridge(s) has been removed, orient the engine so that the crankshaft is in the ' upright ' position, Then measure the end-float on the connecting rod with feeler gauges to be within the service limit. The connecting rods and caps should be marked for identification then the connecting rod cap bolts will be loosened and the number one connecting rod cap and bearing insert will be removed without losing the insert. Sliding the connecting rod/piston assembly down through the top of the engine and if need be use a wooden or plastic hammer handle to push out the connecting rod/piston till you get to the other cylinders. To reassembly put the connecting rod caps and bearing inserts in the corresponding rods but retain the old bearing inserts in their positions during the process to avoid damaging them. The pistons and connecting rods are then taken for inspection and for renewal work to be performed on them if necessary. Piston rings should be examined for space between the ring ends before one puts on new piston rings, the correct rings should match the piston brand. Arrangement of Piston/Connecting rod and new rings for pairing for assembly convenience. Place the top ring into the first cylinder, align this ring with the cylinder wall, and check the end clearance with feeler gauges, if necessary, changing it. Starting with the oil control ring and then the middle and finally the top ring is correct when the gases are on the right of drawing and the combustion chamber 1 above is on the left as shown in figure 2. Ensure that the cylinder walls are free from oil and dirt, chamfer the corner of the bush for Journal bearing and ensure the crankshaft is fitted before the piston/connecting rod assemblies are fitted. Clean and coat the piston and rings with oil, set on the piston ring compressor and ease the assembly into the cylinder. To inspect the connecting rod bearing oil clearance, a Plastigage should be used, but first the surfaces must be cleaned of oil. If the clearance is other than as specified, the bearing inserts or journal diameter may be suspect. Remove all the Plastigage as it can be easily scraped off and apply a thin film of grease or assembly lube followed by the rod cap and new bolts and tighten to the recommended torque. The same process has to be applied for the rest of the assemblies with the additional condition of cleanliness and correct orientation of the part. Lastly, turn the engine over with the crankshaft to look for bind and measure, and adjust as needed, the connecting rod end play.

Prior to removing the piston/connecting rod assemblies, check for ridges formed at the upper limit of ring travel and remove them if necessary. Turn the engine so the crankshaft is facing up. Check the connecting rod endplay with feeler gauges and consult an automotive machine shop if necessary. Mark the connecting rods and caps for identification. Remove the connecting rod cap bolts and the number one connecting rod cap and bearing insert. Push the connecting rod/piston assembly out through the top of the engine. Repeat this procedure for the remaining cylinders. Reassemble the connecting rod caps and bearing inserts and install the cap bolts finger tight. Check the piston ring end gaps and adjust if necessary. Install the rings on the pistons, starting with the oil control ring. Check that the upper and lower side rails can rotate smoothly. Install the number two and number one rings. Repeat this procedure for the remaining pistons and rings. Clean the cylinder walls, chamfer the top edge of each cylinder bore, and ensure the crankshaft is in place. Clean the bearing surfaces of the connecting rod and cap. Lubricate the piston and rings and use a piston ring compressor to compress the rings. Rotate the crankshaft and apply oil to the cylinder walls. Insert the piston/connecting rod assembly into the cylinder bore. Check the connecting rod bearing oil clearance using Plastigage. Clean the bearing faces and apply grease or engine assembly lube. Slide the connecting rod back into place, install the rod cap, and tighten the bolts. Repeat this procedure for the remaining pistons/connecting rods. Rotate the crankshaft to check for any binding and check the connecting rod endplay.

Prior to removing the piston/connecting rod assemblies, check for ridges formed at the upper limit of ring travel and remove them if necessary. Turn the engine so the crankshaft is facing up. Check the connecting rod endplay with feeler gauges and consult an automotive machine shop if necessary. Mark the connecting rods and caps for identification. Remove the connecting rod cap bolts and the number one connecting rod cap and bearing insert. Push the connecting rod/piston assembly out through the top of the engine. Repeat this procedure for the remaining cylinders. Reassemble the connecting rod caps and bearing inserts and install the cap bolts finger tight. Check the piston ring end gaps and adjust if necessary. Install the rings on the pistons, starting with the oil control ring. Check that the upper and lower side rails can rotate smoothly. Install the number two and number one rings. Repeat this procedure for the remaining pistons and rings. Clean the cylinder walls, chamfer the top edge of each cylinder bore, and ensure the crankshaft is in place. Clean the bearing surfaces of the connecting rod and cap. Lubricate the piston and rings and use a piston ring compressor to compress the rings. Rotate the crankshaft and apply oil to the cylinder walls. Insert the piston/connecting rod assembly into the cylinder bore. Check the connecting rod bearing oil clearance using Plastigage. Clean the bearing faces and apply grease or engine assembly lube. Slide the connecting rod back into place, install the rod cap, and tighten the bolts. Repeat this procedure for the remaining pistons/connecting rods. Rotate the crankshaft to check for any binding and check the connecting rod endplay.

Before actual disassembly of the piston and connecting rod assemblies, some of the cylinder head and also the oil pan must be dismantled. The top end of the ring groove needs to be scraped with a fingernail; indelible ridges here must be reamed off as failure will cause a ring burst which will need a new piston. When you have cleared the ridges, ensure the engine is rotated in a manner that the crankshaft is on the top. Measure the dimension of the crank to engine block with feeler gauges which should be less than service limit, if not this is preferred by replacing a new connecting rod. All the connecting rods should be marked to indicate the four cylinders they belong to then, the connecting cap bolts should be removed, however the old connecting cap bolts should be retained for the purpose of the oil clearance exercise. Slowly lift the first connecting rod cap and push the bearing insert out of the cylinder head; the insert must not fall out, and the connecting rod/piston assembly must be pushed out through the top of the engine. Do the same for the other cylinders and then replace the connecting rod caps and bearing inserts; retaining the old ones to avoid loss in case they are needed later. Pistons and connecting rods are finally prepared for inspection and require overhaul. Whenever replacing the piston rings the end gaps need to be inspected and the piston ring side clearance should be set. Position the pistons /connecting rods assemblies and the new rings on checker boards in order to ensure matching before installation. Fit the top ring into the first cylinder and align it as well as possible with the cylinder walls, measure the end gap with the feeler gauges. If it is too small wash with water and if the gap is too narrow filing the ring ends will serve as the best way of widening it. Do this again and again, for each ring; follow the right sequences as well as the orientation in its installation. Just for installation, the cylinder walls must be clean, the edges have to be chamfered and the crankshaft is to be inserted. Remove any dirt from the bearing inserts and set the new ones in the connecting rod and cap, without any lubrication, and make sure they are well positioned. Align the gaps of the piston rings rightly and grease the piston and the rings and its installation may be done with the help of piston ring compressor. Slide in the piston / connecting rod assembly into the cylinder ensuring that the connecting rod is under the crankshaft journal. There should also be a check of connecting rod bearing oil clearance by way of Plastigage and ensure that the width is to the standard prescribed. If the clearance is wrong then cleanliness should be established and the journal diameter can be considered for new bearing inserts. After confirming the clearance, it will be necessary to lubricate the bearing faces, replace the rod cap with new bolts and tighten in accordance with the necessary parameters. This should be repeated for all the assemblies, and it is essential to keep them clean, and oriented in the right directions throughout the stages of the process. Last of all, turn the engine over with the crankshaft to feel for binding and for checking the connecting rod end play; adjust if any new component has been changed.

Prior to removing the piston/connecting rod assemblies, check for ridges formed at the upper limit of ring travel and remove them if necessary. Turn the engine so the crankshaft is facing up. Check the connecting rod endplay with feeler gauges and consult an automotive machine shop if necessary. Mark the connecting rods and caps for identification. Remove the connecting rod cap bolts and the number one connecting rod cap and bearing insert. Push the connecting rod/piston assembly out through the top of the engine. Repeat this procedure for the remaining cylinders. Reassemble the connecting rod caps and bearing inserts and install the cap bolts finger tight. Check the piston ring end gaps and adjust if necessary. Install the rings on the pistons, starting with the oil control ring. Check that the upper and lower side rails can rotate smoothly. Install the number two and number one rings. Repeat this procedure for the remaining pistons and rings. Clean the cylinder walls, chamfer the top edge of each cylinder bore, and ensure the crankshaft is in place. Clean the bearing surfaces of the connecting rod and cap. Lubricate the piston and rings and use a piston ring compressor to compress the rings. Rotate the crankshaft and apply oil to the cylinder walls. Insert the piston/connecting rod assembly into the cylinder bore. Check the connecting rod bearing oil clearance using Plastigage. Clean the bearing faces and apply grease or engine assembly lube. Slide the connecting rod back into place, install the rod cap, and tighten the bolts. Repeat this procedure for the remaining pistons/connecting rods. Rotate the crankshaft to check for any binding and check the connecting rod endplay.

Before the piston and connecting rod assemblies can be removed the cylinder head and oil pan needs to be removed. Feel with a finger on the metal part for any ridges at the maximum limit of the rings travel, which are reqmired to be scraped of by a specialized tool to avoid breaking of the piston. Following removal of the ridges, position the engine in the manner where the crankshaft is on the upper side and measure the connecting rod end play and make sure that it falls within the standard prescribed limits. The connecting rods and caps should be marked for identification and the connecting rod cap bolts then slackened and the cap and bearing insert withdrawn without falling. Remove the connecting rod and piston assembly out through the top of the engine perform the same process as above for all cylinders. That is after removal, tighten the caps as well as the inserts to avoid further damage. During the installation of piston rings, the end gaps, as well as the orientation, should be considered and the piston rings must correspond to the pistons and cylinders. Place the oil control ring more closely to the block after the compressions rings and make sure to place the identification mark to a particular direction. It is recommended that before inserting the piston and the connective rod, the cylinder walls should be free from dirt and the crank shaft should be fitted. New bearing inserts do not need lubrication when being fitted into the engine block, align the piston ring gap appropriately, lubricate the piston and the rings and use the piston ring compressor to guide the piston into the cylinder. Correctly measuring the connecting rod bearing oil clearance should be done using the Plastigage and cleaning the surfaces before applying grease before the final tightening. So do for all pistons and connecting rods, making sure that the surfaces are very clean and that the connecting rods are correctly orientated. After installation use the starter to rotate the crankshaft to check for binding and to check the connecting rod end play and ensure that it is within the limits of tolerance. If so, it may be necessary to work with an automotive machine shop to make them.

Check the ring end gaps and ensure the piston ring side clearance is correct.

Check the ring end gaps and ensure the piston ring side clearance is correct.

12646457 PISTON KIT, ENG