- Joined
- Nov 26, 2009
- Messages
- 3,082
Here's a new drawing of what the Norton head could be. When Norton went from the 650SS to the 750 they simply increased (& offset) the bore and failed to increase the valve size or move them away from each other to allow for increased diameters. The drawing shows the original valve & port layout in green with the new proposed layout shown in red (and black). The valves have been re-angled, seats have a larger outside diameter so even though the original valve diameters can be used - a tuner can open the IDs of the seats and ports leading up to the seats and install larger valves.
The port floors have been raised for increased flow and velocity with a broader curve leading up to the seat. Three floors are shown. The original in green, the Harley XR750 style floor in red and a compromised FA floor in black (re-shaped to more closely match the intake manifold floor angle & with an improved ex port floor).
The ports are cobra head head shaped so they are wider around the guides and I'm working on cross section drawings.
There is actually more material/clearance between the valve spring pockets and the intake port roof than shown in the drawing because the Norton intake valves and spring pockets are rotated on an angle.
The port floors have been raised for increased flow and velocity with a broader curve leading up to the seat. Three floors are shown. The original in green, the Harley XR750 style floor in red and a compromised FA floor in black (re-shaped to more closely match the intake manifold floor angle & with an improved ex port floor).
The ports are cobra head head shaped so they are wider around the guides and I'm working on cross section drawings.
There is actually more material/clearance between the valve spring pockets and the intake port roof than shown in the drawing because the Norton intake valves and spring pockets are rotated on an angle.