I am trying to find out on which side of the scale lies the degrees for before and after top dead center. In the middle of the scale, there are the letters OT, which I understand to be TDC. To the right as seen from standing in front of the car are hash marks in five degree increments, numbered by tens up to the number 80. To the left are hash marks numbered by tens up to the number 20. Is the right hand side of the scale before or after top dead center?