Abstract: A tool for tightening an endless drive belt which includes a jaw having a concave gripping face, a lug-engaging toe projecting from said jaw at one end of said jaw at the terminus of said concave gripping face, an elongated lever arm having a bifurcated bracket at one end thereof receiving and engaging said jaw at a location spaced from said lug-engaging toe, and fasteners adjustably fastening the bracket to the jaw.