From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison of B.T.H. aero magneto distributor dimensions with a suggestion for increasing overlap.
| Identifier | ExFiles\Box 43\4\ Scan240 | |
| Date | 14th February 1930 | |
| E.7.C X4021. Date 14-2-30 Ref No. W.E.6 X.NO. 3832. 4021 B.T.H aero magneto distributor and H.T. Rotor dimensions. We have measured in a similar way to the Watford magneto the dimensions of the distributor segment, H.T. rotor "brush" and distributor pitch which are as follows:- Pitch .77" = 30° of distributor Segment .19" = 7° Brush .28" = 11° Brush + Segment .. = 18° With a 10° range (corresponding to 30° on the contact breaker) there is an overlap therefore of 8° as compared with the 5 1/2 ° of the Watford. We would suggest the desirability of Messrs Norths increasing the overlap on their magnetos slightly, to allow for irregularities in manufacture and in accuracy of distributor timing (gears). HEW | ||