O2 Sensor on a Carb Engine Question

Great for tuning carbs or efi, but they can show what isn't there; the further outside the design pressure of 11-18 psi the greater the error. Also, the further it is from 14.7:1 (when outside the design pressure), the greater the error. No annual cal with heat or no temp compensation circuit increases error too.

Even when reasonably accurate, what if anything should be done about it varies including if you have a lot of overlap (effectively an exhaust leak).