The Edelbrock #5813 Sure Seat Valve Spring for Chevy 4.3L 90 Deg V6 200-262 with O.E Cast iron cylinder heads are made of highest quality spring wire and precision wound to close tolerances. Our 5813 Sure Seat Valve Spring sets are for use on original equipment heads when installing Edelbrock Performer-Plus camshafts. These are the same high-performance springs used on Edelbrock Performer and RPM cylinder heads. For camshaft warranty compliance, use only the springs recommended by Edelbrock for each camshaft application.