I could never find sprocket torque values for my '82, either. I replaced mine, and I picked something in the low 20s, like 23 (ft #) based on the feel, and keeping in mind that it's a bolt with no nut, and that all the torque would end up right on the head of the bolt without a nut to absorb some. In fact, one of the original ones may have broken when I removed it; I seem to remember that.