Abstract: A mounting aid arranged for receiving a valve-actuating sub-assembly intended for installation coaxially about a valve stem. The sub-assembly includes a valve coil spring, a spring retainer having a central aperture and a split collar. The mounting aid has a closing disc having an outer circumference and being arranged for engaging an outer radial surface of the spring retainer coaxially therewith; an axial extension attached to the closing disc at the outer circumference thereof; and hold-back means formed on the end of the extension for releasably securing the sub-assembly to the axial extension.