This listing is for brand new cylinder head parts kit that comes with stock style valves with chrome plated stems, Z28 style performance valve springs, hardened spring retainers and hardened valve locks that are made by Elgin Industries. The Z28 springs are stock outside diameter and can be used as a drop-in compatible replacements for many 1955-1993 small block Chevy V8 cast iron cylinder heads. They work great for stock, towing and most mild performance cams and work best with cams up to 0.500" lift. Intake Head Diameter: 1.940" Exhaust Head Diameter: 1.500", Spring Outside Diameter: 1.260", Spring Inside Diameter: 0.785" Closed: 114 lbs. @ 1.710" Open: 318 lbs. @1.210" Coil Bind @: 1.160" Spring Type: Single with damper