The outer diameter on the damper (where the timing marks are) dictates the distance between the degree marks if that’s what you are asking.  As the diameter changes, so does the distance between the degree marks.  The formula for calculating the distance between individual degrees on a damper is as follows:

(damper diameter X 3.1416) / 360 = degree spacing

If needing to know what the distance is for a given number of degrees from TDC, then you’d simply add the number of degrees you want to the aforementioned formula.  For example, you’d like to know the distance from TDC that 38° is on a 6 ¼” damper.  The calculation is as follows:

(6.25” X 3.1416 X 38°) / 360° = 2.073”

Lorena, Texas (South of Waco)