Harley-Davidson part number 2253 (often produced by brands like Motor Factory or Bender Cycle Machine) refers to a .010-inch thick rocker arm shim designed for Big Twin (1966–1984) and select vintage Harley engines.
Purpose and Function
Reduce End Play: Shims decrease excessive side-to-side clearance (end play) between the rocker arm and the support towers or cylinder head mounting surfaces.
Reduce Noise: Tightening side clearance helps quiet top-end valve train clatter and noise.
Stabilize Alignment: Keeps the rocker arm tracking straight on the valve tip