The bell valve, on the right, is fully hardened & fully balanced. It increased the hp by .5 with the same timming as the inverted drum, on the left, (open 34 deg ABDC & close 63 deg ATDC). The bell valve's weight of 26 gms is 6 to 10 gms lighter than the weight of drum valves found in production motors. The valve runs on one ball bearing & one bushing with no rubbing on the case or the connecting rod. The window in the case is 82 deg wide & the window in the valve is 127 deg wide.This allows the bell valve window to remain wide open for 45 deg. of rotation, which gives the valve an excellent time area number, even though the total duration is only 209 deg.
