Hello to Outdoorking followers

I have read about the various letters on the poppet Valve face and which letter should be located to the emulsion tube for various engines.
However I cant seem to find details specifically for the latest (and sadly last I believe) vex60 engine.

My issue is this.... I put the 'C' there and engine seems to idle and run too high but not what I would call really excessively high.

Questions...
1. Where is the correct position for the vex60 engine?

2. What are the issues in running with the 'C' either side of the Tube?
I have tried both and yes it affects the RPM but what should happen to Idle rpm, max rpm, and mixture if I put it above or below the tube?

Would appreciate it if someone here can help.

Bruce