With narrowband it's an S-curve, 1.0 rich and .4 to .6 is about stoic.
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Most ECUs don't care about keeping perfect 14.7 (and rarely do for good reasons). Here in 10% ethanol land stoic is more like 13.x anyway so I want it richer for that and which puts it out of the top of the vertical middle plot. Then also, I live at altitude which implies I want leaner.
Want to know how to tune your Holley carburetor for when you are driving in the thin air of higher altitudes? By using some simple measurements and some basic adjustments, your carb can be happy no matter how high up the mountain you intend on driving!
www.holley.com
And, to top it off, the 413 RV models are stagger-jetted