I have a question about A/F readings and a cam

TrailBeast said

The gauge was stable as a rock for two years, and the 318 was smooth as glass with that same carb.
Also, I can make changes with one idle circuit or the other and it changes to rich and lean both but doesn't get any better about the A/F than about the 10-11 I mentioned.
I can make it worse. :D

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Then it's probably the mix, not the cam, and a lot to do with the timing. 20" is decent even for a stocker. I'd pull the initial down to 12-14, hook the v can to manifold vac and then try leaning it. Bigger cams may like more idle mix, but I'm willing to bet that they'll idle lean just fine with the timing set well enough.