Feuling Rocker Shaft Shims For Harley Adjust the rocker arm to cylinder head end play clearance to quiet your engine. The rocker arm standoff trusting surfaces on M-Eight cylinder heads are also excessively worn placing the hardened shim on the thrusting side will help prevent additional wear and damage to the cylinder head. Features: Feuling recommends an ideal side clearance of 0.035 - 0.005 for optimum rocker arm oil psi and noise reduction Individual sizes sold in a 6 pack Kit includes (6) 0.003, (6) 0.005, (6) 0.010 shims Made in the USA Note: These shims should be installed by a professional, one who can make correct end play measurements and can install and tighten rocker shaft nuts/bolts without damaging shims.