A lever-operated clamp having a base, a clamp arm pivotally mounted to the base, and a lever which, upon pivoting, moves the clamp arm in a clamping direction of movement. An internally threaded bolt retainer is mounted to the clamp arm and threadably receives a bolt so that the rotational position of the bolt relative to the bolt retainer varies the position of the bolt relative to the clamp arm. A jam nut or internally threaded knob locks the bolt at its adjusted position.