ORIGINAL: alex7403
Let me ask it this way how bad is it if the break in went when the low end mixture valve was not adjusted and the engine was not running smooth
and adjusted later?
With the majority of glow engines, you cannot damage the engine regardless of where the low speed needle is set. It just won't run properly. There used to be some engines in the past (Fox) that could be damaged by running too lean of a low speed mixture. I am not aware of any engine produced today that works the same way as the Fox.
Running a ringed engine very rich through the break-in period is almost always the proper thing to do. They will vibrate, miss and jump around some if your engine mount or model isn't all that solid. That is normal.
Be sure to check all of the fasteners for tightness. In fact, this is a good thing to do several times a year anyway, assuming that you are flying this engine regularly.
Congratulations! It sounds as though you got through the break-in period successfully. I hope you get many, many enjoyable flights with your top notch OS engine.
Ed Cregger