The circumferance can be calculated from the 170mm diameter x 3.14 , it means 5 degrees is about 7.5mm around the circumferance on a standard pulley so 10 degrees is 15mm
easier imo than trying to measure angle in degrees
u shape is tdc v shape timing mark, engine rotates clockwise so timing mark is to the rhs (clockwise) of tdc for btdc timing as dg dj, other way round for atdc timing as on df