Join Date: Aug 1998
Location: Waldorf Md. USA
Most torque wrenches are not very accurate at the extreme ends of their range. For instance, a 0-200 lb ft wrench will not be accurate at 20 lb ft. If you look at the accuracy ratings, even the best ones are usually plus or minus 5% That is 10lbs on a 200 lb wrench. Actually, at 12 lb ft I would be using an lb in torque wrench set at 144 lb inch.
Either way, if the carb bolts are coming loose at 40lbs...something is wrong. I would do as drake said and borrow another wrench to compare it to.
Hope this helps,
Advanced Automotive Machine