Idle Speed. What makes it right?

Ok gotcha. We all learn regardless of how much experience we have. The quest never stops. Idle vacuum is a good indicator of efficiency. As you increase timing at idle vacuum will go up until the engine looses efficiency. The idle timing should be kept around that number. Whatever it ends up being. Lots of things effect what that number is. So each engine is different. Fuel will do the same thing. Lean it out and watch the vacuum and rpm. Fatten it up and do the same. You’ll find the sweet spot. The idle quality will degrade going too far both ways too rich or too lean. After you’re happy with the afr and timing at idle you can set the desired rpm. Once that is set go back and do the timing and fuel adjustments again to see if anything changes. Sometimes it can be monotonous but it’s how it’s done. Good luck.