I made this cheat sheet for selecting jets and idle mixtures with a four-gas analyzer. The source article I got it from is out there if someone wants to look for it. I think the author deserves credit, but I can't recall his name.
The red vertical line14.3:1 is the recommending mixture for idle in comparison to the 14.7:1 automotive industry's theory. When the engine goes off idle it will go lean, but as you see here recommends a richer 12:1.
You can observe when CO is low and HC is high, a production of Nox is high(see the chart), which is the killer in enclosed garage. I like to stand as far possible from the rear of the idling car at all times.
That vertical gray bar in middle of chart is where exists ideal conditions for proper combustion. Another way to check is condensation at the tail pipe when the CO2 is high. The Nox is at lowest when the mixture is on the rich side. In summary carbs like a gaseous solution of rich mixture and not necessarily more fuel.
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