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.

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.

A fluid end assembly of a hydraulic fluid pump includes a housing having an axial bore, a removable valve cover closing the axial bore, and a retainer engaging the axial bore. The retainer includes a central opening. The fluid end assembly further includes a threaded drive member positioned within the central opening and operable to apply a preload against the retainer.

An engine block comprising: a combustion chamber, an inlet for introducing a fuel/air mixture into the combustion chamber and an outlet for expelling combusted fuel/air mixture from the combustion chamber; and a piston that reciprocates within the combustion chamber to compress the fuel/air mixture therein, the piston having a closer supported thereon, wherein reciprocating movement of the piston seals the combustion chamber with the closer.

An engine block comprising: a combustion chamber, an inlet for introducing a fuel/air mixture into the combustion chamber and an outlet for expelling combusted fuel/air mixture from the combustion chamber; and a piston that reciprocates within the combustion chamber to compress the fuel/air mixture therein, the piston having a closer supported thereon, wherein reciprocating movement of the piston seals the combustion chamber with the closer.