RE: O.S. 18TM Tuning
We're not sure what you mean when you refer to leaning by 30 or 45 degrees. Are you referring to temperature or angle?
At any rate, we never pay attention to either. We richen or lean according to the engine's performance and go a small amount at a time. If you only go in 30 or 45 degree increments, you'll never get the engine set correctly because the actual spot may be at 20 degress (for example).
There aren't any set points we can give you. You have to adjust the engine by sound and performance. The settings will change when you change gear ratios, change fuels, and have weather changes. Usually, though, once an idle mixture is found, it doesn't have to be reset very often at all. It's the high-speed needle that should take the major changes.
A cooler day means that the high-speed needle will need to be richened. Cooler air means that the engine is pulling in more air by weight, which means you need more fuel by weight to keep a proper mixture.