To have the valve covers taken off, you need to first undo the rocker arm fulcrum bolt and washer and the rocker arm. If only the pushrods are being removed, then the loosening of the fulcrum bolts is required and the rocker arms bound to be pushed to one side so that the location of the removal of pushrods can be accessed easily but the pushrods are organized in a particular fashion for reinserting them back a particular place in the car possibly with the help of a perforated cardboard box. The rocker armsshould also be checked for any signs of wear, craks and damage especially around the contact end with the pushrods and /or valve stems while ensuring the small hole on the poshrod end of the rocker should not be blocked. Look for signs of wear and galling of the fulcrum contact area; if there is any sign of wear or damage of any rocker arms replace them with the fulcrum seats. All the pushrods should be examined for cracks or worn areas and, although slightly more difficult, each pushrod should be rolled across a flat surface to ensure that it is straight. For fit-up, use engine oil or assembly lube to the top of the valve stem and in the pushrod guide, at the rocker arm fulcrum seat and socket. Place the pushrods after which the rocker arms, the fulcrums, and the fulcrum bolts come into play. Turn the crankshaft in order to bring the lifter down far as possible, then fasten the fulcrum bolts to the established extent of turn. Last of all, reinstall the valve covers and gaskets, crank up the engine, and, if there are any roughness or noise, you're done.