[Raceboy]

Originally Posted by Steve@Rennsport

JMHO, but thats too lean for air-cooled engines and this is especially important in hot weather.

13.0-13.2 is OK for light throttle cruise, but WOT, full-load should be 12.6-12.8 for the engine to survive.

I should have been more specific, 12.7-12.8 in max torque area and can lean up to 13.0 at higher rpms.
Regarding cruise, target afr is a combination of many things, but I forgot that he does not have programmable ignition, because with leaner afr one can advance ignition so the EGT's are cool and not transfer heat into heads from exhaust ports. I have tuned quite a few normally aspirated 911 engines like I described, so far they have been running for few years on the track and on the street (even long road trips to western europe). But we have only hot summers, not all year long.

Just my 2 cents.