One area often over looked after an engine has been bored and honed is the bottom of' the cylinder. If this burr is not removed it can cause piston scuffing. The sketch below depicts a piston at the bottom of the stroke.

In newer engines much of the piston skirt protrudes from the bore at the bottom of its travel and when it begins its upward travel it cocks or cants in the cylinder. If there is a burr at the bottom of the cylinder, aluminum will be spalled or rubbed off and cast iron transferred to the aluminum. These particles can break through the oil film and scuffing is started. In some cases it may get progressively worse until the engine fails.

Crocus cloth, Scotch Brite®, or some similar material can be used to remove the burr.

For additional bulletins, order Form No. H521.

(P74)