Abstract: A clamp assembly having a base and an elongated clamp arm having one end pivotally mounted to the base. An elongated lever is pivotally secured to both the base and the clamp arm and movable between a first and second position which simultaneously pivots the clamp arm along a direction of movement between a hold position and a release position. A bolt retainer is attached to the free end of the clamp arm. The bolt retainer includes an internally threaded bore having an axis which extends substantially parallel to the direction of movement of the clamp arm. A bolt includes a portion threadably engaged in the threaded bore so that the effective length of the bolt is adjustable by rotation of the bolt in the bolt retainer bore.