Many of the popular engine families utilise a positive stop type of rocker are attachment, which does not allow for any adjustment, and consequently, there is no consideration for different cam sizes or other modifications to the engine block or head. For that reason, COMP has designed a kit to convert this set up to a fully adjustable valve train. On the Ford 302 - 351W, simply remove the standard adjusting nut, slip the spacer over the stud, install the new nut and adjust the valves as necessary.