ISKY Ultra-Rev Kit Machined Aluminium Rev Plate, Hard Coat Anodised Suit SB Chevy Bow-Tie Blocks with Raised Lifter Bosses (ISK1350-LRK)SBC ULTRA REV KIT Ultra Rev Kit Machined Aluminium Rev Plate, Hard Coat AnodisedSuit SB Chevy Bow Tie Blocks with Raised Lifter Bosses Part Number: ISK1350 LRK The "ULTRA REV KIT" is engineered to increase engine RPM and prolong roller tappet bearing life by pre loading the roller tappets to the cam lobe (eliminating stop start "Skidding".) Pre load springs are held in place by lightweight aluminium retaining bars which install beneath the cylinder