Using O2 sensors in analogue for mixture reading

Hi
I have an interesting question for You. I have an early kit car 3 wheeler made from a citroen 2cv. as she predates obd2 by some
40 years she is purely analogue'.however I saw that putting a voltmeter across an o2 lambada sensor it will produce a reading
in volts (millivolts). I have fitted My twin exhaust system with 2 o2 sensors,one on each side and I can use the readings to
balance the mixture between my twin carburetors. But I don't know what voltage reading an o2 sensor should be for correct fuel/air mixture, so please can You help with what this reading should be?
I love watching Your Utube channel, and I have learnt so much just by watching You work.
Kind Regards
Jahmahrah De'Safilli

If you gave a link or a description of the specific sensor you are using that would be helpful. 

You're largely wasting your time with narrowband sensors as they only really give an indication of rich/lean vs stioch. That said, stioch should be in and around 0.5-0.6v, with richer being higher. But as it is so non linear, it will be difficult to use for the purpose you want.

secure.lambdapower.co.uk/TechNotes/Tech-4.asp

Plus if it's only idle, they would need to be heated sensors to be usable.

If you want decent mixture data, just buy a wideband kit, ideally one per bank if the engine has more than one bank of cylinders and independent exhausts ( or fit the sensors prior to any exhaust merge )

Or for an easier visual on it, you can do this.

www.edproject.co.uk/NarrowAFR.html

However having used these 20+ years ago....again, you have to appreciate the limitations of a narrowband sensor to even try and make use of it.

Nowadays, waste of time and money when wideband kits are so cheap and will give you proper data