I realize today that I didn't have a clue about which way to turn sync screws to have to right result while performing a running sync. In other words, if I want to give more vacuum to carb #3, do I have to screw in or out? I thought i may not be the only one so I decide to share a few pictures with the forum. To answer this, I put a carb rackI have on the shelf. Here is a general view: Let's do it in the same order recommended in the manual, starting with carbs #1 and #2. If your vacuum gauges show that #1 sucks less than #2 , you should do this: Second, we should balance carbs #3 and #4. If readings are lower for carb #4, you should do this: Finally, to balance 1-2 pair with 3-4 pair, if 1-2 pair readings are lower , you should do this: In other terms, first and second sync seem counter-intuitive, if you want more vacuum on the left , turn to the right. The third one is intuitive, if you want more vacuum on the right, turn to right. I hope it could help.