Spark Plug reading

[trevarthan]

Originally Posted by HO455

Unfortunately in these modern times of ethanol gasoline, every brand having a different mix of additives, and the change in fuel mixtures for the different seasons of the year, being able to read a spark plug with any kind of accuracy is impossible. If you were to run only straight AvGas then you would be able to read a plug like in the days of yesteryear.
On the up side of these modern times we now have wide band O2 sensors and the ability to read air/fuel ratios on a guage with far greater accuracy than what you can get by reading plugs. For example:

http://67-72chevytrucks.com/vboard/s...d.php?t=713728

This is the first time I've heard anyone say this. Do you have any data to back up this claim? I'd like to know more.