Abstract: Improved rocker assemblies for use in opening a valve in an engine are disclosed, along with an improved method of assembling the rocker assemblies. The rocker assemblies have pivotable rocker arms with rocker balls and sockets as in the prior art. A retainer is used to secure the sockets on the rocker balls, as in the prior art. Novel retainers are disclosed that are made of either thermoset, thermoplastic or epoxy polymers. At least part of the retainer extends beyond the socket to a position between the top of the socket and the end of the rocker arm. The retainer may extend along the side of the socket to the socket bearing surface, and may have one or more channels to deliver lubricant to the bearing surfaces of the socket and the valve stem. The retainer may also have spacers that extend beyond the level of the socket bearing surface to define the desired valve lash distance between the socket bearing surface and the valve bearing surface.