Roller-tip rocker assembly. 1.5 Hi-Lift for 1275cc big bore engines only. To use on small bore heads it is necessary to rearrange the rockers to line up the tips with valve stems. The ultimate lightweight alloy valve gear giving maximum efficiency cutting down side loading on valve stem, reducing friction and wear whilst increasing rigidity. The 1.5 hi-lift keeps valves open approximately 20% more at any given point, although opening and closing periods remain the same, and vastly improves volumetric efficiency and, therefore, power output. The alloy rockers have hard chrome roller tips and original bronze bushes for a competition thick-wall Mini shaft, standard adjuster screws and nuts are also employed. These combine in a high quality yet economical roller rocker set, as the roller tip is the most important factor to reduce valve and guide wear when using modern performance cams. The set comes with 8 rockers, adjuster screws and nuts, competition thick-wall shaft and steel pedestals. 4 Head Nuts part number 51K1193 are also required to replace the front rocker pedestal nuts. The standard nuts won't clear the rocker tips.