Max Valve stem diameter 40 mm; Minimum valve head diameter at 45° with steady rest: 15 mm: Minimum valve head diameter at 45° 200 mm: Minimum valve head diameter at 30° 200 mm: Grinding wheel motor stroke: 95 mm: Graduated quadrant stroke: 150 mm: Minimum length with steady rest 45° 180 mm: Minimum length without steady rest 45° 95mm ...