[Shiny]

Sorry if this is basic to most of you, but here's my random question for the day following recent attempts to learn about and getting help with both my distributor and carb tuning.

If the A/F is being measured AFTER combustion, does the timing affect the readings or is it only affected by the A/F mixture?

Does an A/F meter measure CO or CO2 to O2 ratios (combustion products) or can it also sense unburned gas (total hydrocarbons)?

Given the "degree of combustion" is controlled by both timing, gas/air ratios, and loads on the engine, how do you use an A/F meter to separate timing from carb tuning?

My impression is A/F meters are used to optimize carb and/or FI tuning after a timing curve is set, which suggests timing and fuel/air ratios are somewhat independent ????