Competition Cams 4716 1.320" Spring Seat Cutter for Vortec Heads, .630" Guide Cuts spring seat to 1.320 inch O.D. Cuts guide to .630 inch Cuts seat to install larger springs and hardened spring seats on GM Vortec heads Other seat cutters available in many sizes from 1.350 inch to 1.810 inch O.D. Easy installation