Cylinder Block: Fitting Pistons

Inspect pistons and replace any showing signs of excessive wear, wavy ring lands, or fractures. Replace piston if sponge-like or eroded surface is on edge of piston top (caused by detonation or pre-ignition).
Note if shiny surface on thrust side of piston is found, check for bent connecting rod. Replace piston and/or rod as necessary. Inspect connecting rods for signs of fracture and bearing bores for out-of-round and taper.
If bore exceeds recommended limits and/or rod is fractured, replace rod. Check pistons for fractures at ring lands, skirts and pin bosses. Check for scuffed, rough or scored skirts.
Check piston-to-cylinder bore clearance by measuring piston and bore diameters. Inspect cylinder walls for scoring, roughness or other signs of wear. Check bore for out-of-round and taper. Cylinder bore out-of-round limit is .0015" (.038 mm), and service limit is .005" (.127 mm).
Cylinder bore taper should not be more than .010" (.254 mm). Measure diameter of cylinder bore at top, middle and bottom with gauge at right angle and parallel to centerline of engine. Measure outer diameter of piston at centerline of pin bore and 90 degrees to pin bore axis.
If cylinder wall is severely marred and/or worn beyond specifications, refinishing will be necessary. Before any cylinder refinishing, ensure that main bearing caps are in place and tightened to specification to avoid distortion during refinishing operation.
After refinishing and before measurement, clean bore with soap/water solution and oil cylinder walls. Ensure piston and cylinder bore are clean, dry, and at room temperature: 70°F (21°C) during measurement. After any refinishing operation, allow bore to cool.