Cylinder Block Assembly: Testing and Inspection

1. Visually check the engine block for scores, rust and corrosion.Also check for cracks or any other defects. Repair or replace the block if defective.
2. Using a straight edge and feeler gauge, check the block top surface for warpage (see image). Make sure that the surface is free from gasket chips and other foreign matter.
Standard: 0.05 mm (0.0020 inch) or less.
Limit: 0.10 mm (0.0039 inch).
3. Measure the cylinder bore with a cylinder gauge at three levels in the directions A and B.
- If the cylinder bores show more than the specified out-of-round or taper or if the cylinder walls are badly scuffed or scored, the cylinder block should be rebored and honed.
- New oversize pistons and rings must be fitted. Measuring points are as shown (see image).
Standard cylinder I.D: 75.50 mm (2.972 inch).
Cylinder taper: 0.02 mm (0.0008 inch) or less.
4. If a cylinder ridge exists, cut away with a ridge reamer.
5. Oversize pistons are available in four sizes
- Piston service size and mark.
1st. O.S. (marked 25): 0.25 mm (0.0100 inch).
2nd. O.S. (marked 50): 0.50 mm (0.0200 inch).
3rd. O.S. (marked 75): 0.75 mm (0.0300 inch).
4th. O.S. (marked 100): 1.00 mm (0.0390 inch).
6. When boring the cylinder bore to oversize, keep the specified clearance between the oversize piston and the bore, and make sure that all pistons used are of the same oversize.
- The standard measurement of the piston outside diameter is taken at a level 12 mm (0.4700 inch) above the bottom of the piston skirt and across the thrust faces.
- Piston-to-cylinder wall clearance 0.025-0.045 mm (0.0008-0.0016 inch).