If a cylinder bore is scored 0.004 inches deep, to what oversize should it be refinished?

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

Answer: (C)

When a cylinder bore is scored, you remove enough material to wipe out the damage and leave a true, uniform bore surface. The depth of the score helps guide how much material to remove, but you also aim for a final bore size that matches standard oversize steps so the piston rings and clearance stay correct. A score 0.004 inches deep is typically addressed by going to the next standard oversize, which is 0.010 inches. This removes the damaged area and leaves a clean bore with safe wall thickness and proper ring seating. Oversizing only a little more, like 0.005 or 0.008 inches, might not fully remove the score, while oversizing to 0.020 inches would be excessive and affect fit. So 0.010 inches is the practical, standard choice.