if you have a mark that's 5 degrees, and a TDC mark, then 20 degrees would be back another 3 spaces of the distance from TDC to 5 BTDC, i.e. 4 5 degree intervals would be about 20....
to me this sounds like a WHOLE LOT of advance. My supercharged lincon only got like 12 degrees, but hey, what do I know, it could be a difference in how the distb is set up and how it delivers spark.
