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).
American battery ignition systems, including current draw, coil construction, and the move away from magnetos.
| Identifier | Morton\M20.1\ img001 | |
| Date | 1st April 1924 | |
| R.R. 235A (100 T) (S.H. 159. 11-8-20) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 2800 ORIGINAL TO EFC. } FROM R.{Sir Henry Royce} Copy to CJ. RG.{Mr Rowledge} HS.{Lord Ernest Hives - Chair} DA.{Bernard Day - Chassis Design} BY BATTERY IGNITION. R2/M3. 4. 24. 3199 X918 Mr. Olley tells me "that American battery ignitions take 1 1/4 amps. @ 6 volts = 7 1/2 watts Bosch U.S.A.". Therefore our running current ought then to be .625 amps 12 volts, with a possibility of running with from 6 to 8 volts at moderate speeds to get an engine started with a low battery. RR. USA. have decided that magnetos are not so reliable because machines are not now made for high class cars. Tungsten points are better and more reliable and a fraction of the cost compared with platinum; throw away these when damaged. Coils are now made by several USA. constructors with nearly closed in circuits with some advantages either in improved ignition or less current, or less fine copper wire. [Diagram of a coil] Laminated sheet iron, say Stalloy. .08 gap about. The ignition only taking a small amount of electrical energy might alter my opinion about double ignition. American fibre known as 'Bone' (hardness), & Grey (colour) is the material they have found best for contact maker blocks. R.{Sir Henry Royce} | ||