1970 Dodge Dart 318 piston rings

nm9stheham said

FWIW... don't think I've ever observed less wear at the top than in the middle.... but can't say I consistently paid attention to the middle.

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The piston speed is maximum at mid stroke, it's slowing down to change directions at the top and bottom of the bore.... Also by mechanics/physics, the maximum side load is when the crank is 90° from the bore... Those two together would typically mean that the greatest wear is in middle of the piston travel area when the crank is at 90°...