WOT depending on fuel can be anywhere from 12.0 to 13.0
Cruise I like to see in the high 13's at a minimum. If you can run above that and not have issues, economy gets better as a general rule.
I agree x 100
Use the AFR as a tool, but you will need to tune what the motor wants.
As an example my AFR is 12.8 at idle in N, drop in gear and I'm at 13.5, any leaner at idle and the idle circuit goes unstable. I've tuned my carb for a flat 14.0 at light cruise, and 12.5 WOT. If you are going to race, the rule of jet for MPH works better than the gauge reading IMO.
Here's a good read for dialing in a carb. It's time consuming but worth the effort and will give you fuel injection throttle response. Carb Tunning
