Michigan Motorsports 0.060" Valve Spring Shims for LS Heads with Stock Guides Pack of 16 Shims These shims are .060" thick with a .510" inside diameter and 1.260" outside diameter. Commonly used for setting installed height with dual valve spring kits. Will not work with larger diameter bronze guides. A 2-piece valve spring locator seat and seal setup must be used with these shims. These shims should not be used under 1-piece "tophat" style seals with the integrated spring seat.