BRIAN CROWER SINGLE VALVE SPRINGS & RETAINER KIT - 3SGE. 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. Please select which spring type is required from the drop down menu based on specs below: BC0350S-2 - Single Spring/Steel Retainer Kit (Shim Over /Shimless): Type BC1300-16 Single Free Length 1.690" Seat 1.325" @ 80 lbs Open 0.980" @ 158 lbs Coil Bind 0.810" Retainer BC2300S-16 Spring Seat OEM Net Cam Lift 0.460" / 11.68mm BC0350-2 - Single Spring/Titanium Retainer Kit (Shim Over /Shimless): Type BC1300-16 Single Free Length 1.690" Seat 1.325" @ 80 lbs Open 0.980" @ 158 lbs Coil Bind 0.810" Retainer BC2300-16 Spring Seat OEM Net Cam Lift 0.460" / 11.68mm BC0350 - Single Spring/Titanium Retainer Kit (Shim Under Bucket): Type BC1351 Single Free Length 1.670" Seat 1.350" @ 85 lbs Open 0.900" @ 200 lbs Coil Bind 0.820" Retainer BC2351 Spring Seat OEM Net Cam Lift 0.460" / 11.68mm