GM 14020567 PIISTON

The piston has to be properly connected to its respective connecting rod; it is very delicate and if one is not well experienced he or she should obtain the necessary help and an arbor press. New piston rings should be of the same size as the piston that is to be used and their fitting is important in the performance of the rebuilt engine. Before fitting the rings identify the correct size of the ring end gap for each set which is usually made up of a top ring, a second ring and an oil-control ring set. Place a top ring land into the cylinder bore ¼ inch below the upper limit travel and be sure to align the ring with the cylinder wall with the help of a piston. Insert a feeler gauge between the ends of the ring and if the gap is less than that specified then a new ring must be used. Do this for all the tops rings and if there is need, the two ends may be matched with a fine file. Roll the piston ring around the groove to make sure that it fits tight into the groove, a distorted ring should be replaced. When fitting the piston rings the relative positions of the gaps should be maintained, the use of a piston ring expander tool, if available, is preferred but small lengths of tin can also be used as an aid to ensuring that they are in the correct location. Put on the bottom oil ring spacer and its parts, which should have the gap at the indicated position and check the gap of the piston rings in the grooves with the blade feeler gauge and replace or adjust the rings accordingly.

After removing the ridge, crank the engine to the top of the cylinder to remove the cloth and cuttings, as failure to do so may damage the piston rings, pistons, or cylinder walls.

A wooden hammer handle can be used to tap the top of the piston slightly while holding the ring compressor firmly against the cylinder block until all rings are inside the bore.

If the cylinder block requires any machine work, including finish honing, the machinist will likely want the pistons available to check piston-to-bore clearance as the cylinder walls are cut, making this measurement critical and best left to the machine shop.