HKS 85-91 Toyota Corollla / 85-89 MR2 4AGE Cam GearCAM SPROCKET Accurate valve timing control (angle adjustable) As cam duration and other engine specifications changes, the ideal valve timing point will also change. As both intake and exhaust cam duration increase, the overlap amounts can be adjusted for optimum performance. All HKS Camshafts come with recommended valve timing which can be achieved by using these sprockets in conjunction with HKS camshafts. These sprockets are compatible with