With 3/8" (9.525mm) ø pilot, will give upto 600" valve lift. 5/16" (7.9375mm) pilot is required for thin stem valves. Used to lower the lower valve spring collar in high lift applications where spring travel is insufficient or spring pressure too high.

Note: See 516675 for 5/16" (7.9375mm) pilot and 516676 for 11/32" (8.7313mm) pilot.