How lean is too lean?

Guys (and gals?),

I don't know how to ask this accurately, or any clear than I have below, so bear with me. I've searched all over the internet and I'm not finding what I am trying to find. I'm guessing it is because, it is a very complex issue.

I've always heard that damage caused by a lean fuel mixture is only at WOT. But maybe that was all I ever heard … back in my Wankel rotary engine days. I'm going to assume that it is true for piston engines as well. But to a degree. Meaning, at cruise rpm, there's not the same cylinder pressures or heat (as WOT) so running lean at cruise rpms is not bad. But if it is too lean at cruise speeds it will just lose power (or maybe build heat also).

Here's my condition, which leads to my question. I have my Edelbrock 1405 equipped LA360 cruising at say 45 - 60 mph in the 14.0 - 14.5 AFR range. But when I go to accelerate (not WOT, just accelerate at all), what happens when my foot pushes on the pedal? I'm not (directly) adding gas, but I am directly adding air by opening the throttle valve. So, my 14.0 - 14.5 AFR at cruise immediately gets leaner when I open the throttle. I'll hit 15.5 - 16.0 AFR trying to pick up speed. So here's the question: At this non-WOT condition, where is the threshold that XX.X AFR (lean) is OK, but YY.Y AFR is too lean and could lead to problems, even at this power mode / cruise rpm? Or … is this lean condition not an issue because I'm not at WOT?

The way mine runs even at these high / lean AFR numbers, it runs very strong. If I didn't have an AFR gauge on it, I would not even know it was lean, as it runs great.


7milesout