Are you referring to initial or total timing by that mark? Is the initial timing closer to the end of the ground strap or the base? Ive seen some charts and they show being able to see 2 timing marks on the ground strap?
Change of color up towards the tip is late timing, and more towards the threads is too much.
Middle of the bend is about perfect IMO.
If you idle or low rpm a lot then yes, idle is a bit rich.
(And I still think it may also be too hot a plug)
