I suppose you're talking about leaning one out? I've done it a few times with Holley's, but in general, anything more then a "step" leaned them too far. If we're on the same page, we are talking about the primary side here? The factory setup on most street carbs is about as lean as they like to run, from what I've seen.
If you're trying to lean a "big" carb to run on a mild combo, while worthy of trying, I'd look to step down to a smaller unit at some point.
