A fluid end assembly of a hydraulic fluid pump includes a housing having a bore, a removable valve cover closing the bore, and a retainer engaging the bore. The retainer includes a set screw bore that extends from a first side of the retainer to a second side of the retainer, opposite the first side. The fluid end assembly further includes a set screw. The set screw is threaded into the set screw bore from the first side of the retainer. The set screw is not removable from the second side of the retainer. The first side of the retainer is positioned adjacent to the valve cover.