No two engines of the same type run with the same needle settings at the same place at the same time. Period!!

ALL engines need to have the needles set to the elevation, the temperature, the humidity, and the prop. Always.

The manufacturer settings and manual notes are for starting points only, and not the "gospel" positions that they should always be at. It just can't work that way.

I don't mean for this to sound harsh, I really don't, but you will have to play with things until you find the right settings for YOUR engine. There are many, many others that could stand a little enlightenment in this area, so hopefully your post will help them, too.

BTW, a few small air bubbles are nothing to worry about.

Pat