Formula First Valve Information

5.6.5. Valves and valve seats may not be reshaped. Valve to valve seat mating surface (figure 1) shall be cut as follows. The 45 deg valve seat width (figure 2) shall be maintained by cutting a 15 deg chamfer (figure 3) at the outside edge of the seat and a 75 deg chamfer (figure 4) at its inner edge. Seats cannot be refaced if too little material remains for a 15 deg chamfer to be cut without going beyond the boundary of the insert. If the chamfer extends to the head, the head must be replaced.

Figure 1

Figure 2

Figure 3

Figure 4

5.6.5.1. Valve specifications (figures 1 & 5):
Dimension “a” – valve seat contact width: Intake – 1.30 mm to 1.60 mm
Exhaust – 1.70 mm to 2.00 mm Seat contact angle on valve: 45 deg Intake and Exhaust
Dimension “A” – valve head dia: Intake – 35.56 mm max. Exhaust – 32.06 mm
Dimension “B” – valve length: 110.5 mm to 112.5 mm
Dimension “C” – valve stem dia: Intake – 7.94 mm min. Exhaust – 7.91 mm
Dimension “b” – valve head margin: Intake - .80 to 1.50 mm Exhaust – 1.00 to 1.70 mm
Dimension “d” – face angle of valve only: Intake - 44 deg Exhaust – 45 deg