Designed for high rpm, BC valve springs by PAC Racing are wound from only the highest grade, super clean, chrome silicone alloy and feature proprietary processing procedures for consistent pressures. BC retainers are machined from premium chromoly steel alloy for "set it and forget it" wear characteristics. Beehive spring keeps retainer lightweight. Also includes BC3991-2 valve stem seals.

NOTE: Does not work with over .430" lift camshafts. Retainer to seal contact will cause extensive damage to the head.