I was rebuilding my 2 barrell carb and I started to tighten the power valve on the bottom of the carburetor when it snapped. I took it out and showed the parts store where i bought it and told him I think it was defective because i did not tighten it tight and it snapped and he told me they are pot metal you don't really tighten them up little more than hand tight.  I told him the old one tightened up fine but he charged me for a new one 9.00. I would like to know what is the correct torque on them so I do not have to buy another new one.