BTR SK427 SPRING KIT - SOLID ROLLER LSx - SK427/500 When you take the plunge into a solid roller combination, taking the guesswork out of the valvetrain combination is a huge relief. For that reason, BTR is proud to introduce the SK427 valve spring kit. Parts included: (16) SR532 titanium retainers (16) PSI-DR427R ML valve springs (16) VS LS valve seals (32) VLM8-8MM-1 valve locks (16) SLS128-1 locators (stock guides) Spring specs: Type: Dual Spring OD: 1.300″ Inner ID: .628″ Seat: 230 lbs @ 1.850″ Open: 715 lbs @ 1.100″ Recommended Lift: .750″ NOTE: Please check valve guide clearance if you exceed .650 - .660 lift.