To what size should a cylinder be refinished if it was scored 0.004 inches deep?

To what size should a cylinder be refinished if it was scored 0.004 inches deep?

• A. 0.010"
• B. 0.005"
• C. 0.008"
• D. 0.020"

Answer: (A)

When a bore is scored, you finish it to a standard oversize to remove the damaged material and provide a fresh, round surface for the new rings. The deepest score is 0.004 inch, but you don’t stop there—you go to the next standard oversize so all damage is eliminated and proper cross-hatch and clearance are achieved. The standard oversize after the nominal bore is 0.010 inch, so the cylinder should be refinished to that size. Finishing to smaller nonstandard amounts wouldn’t align with typical oversize practices, and going to a much larger size would require different pistons and rings. After selecting the oversize, verify piston clearance per manufacturer specs.

When a bore is scored, you finish it to a standard oversize to remove the damaged material and provide a fresh, round surface for the new rings. The deepest score is 0.004 inch, but you don’t stop there—you go to the next standard oversize so all damage is eliminated and proper cross-hatch and clearance are achieved. The standard oversize after the nominal bore is 0.010 inch, so the cylinder should be refinished to that size. Finishing to smaller nonstandard amounts wouldn’t align with typical oversize practices, and going to a much larger size would require different pistons and rings. After selecting the oversize, verify piston clearance per manufacturer specs.