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).
Technical memorandum detailing the specifications for magneto and battery ignition timing and control angles.
| Identifier | ExFiles\Box 65\1\ scan0216 | |
| Date | 19th September 1928 | |
| EFC. )from R.{Sir Henry Royce} Hs.{Lord Ernest Hives - Chair} } By.{R.W. Bailey - Chief Engineer} C. to BJ. WOR.{Arthur Wormald - General Works Manager} X7680 R1/M19.9.28. EAC.10 IGNITION. X.7680. X.928. X.8680. X.3949 To get uniform angles in the controls we want to get the magneto range angle increased from 58° to 60°. This will be 40° on the flywheel. Of this 40° we use it as maximum position 45° advance by hand and auto. and latest position by hand and auto. of 5° B.D.C. The angle of auto;advance is to be 25°, and of hand advance 15°. The battery ignition total control will be from 45° total advance (25° by auto:) to 10° A.D.C. = 30° by hand, total 55°. (All given in flywheel angles). We are assuming that 45° B.D.C. is the maximum ever required. 30° hand range is sufficient for starting on switch and 25° auto. control will be sufficient for ordinary running. We have modified this to give more hand control, so that wrong setting can be corrected as long as the two ignitions are synchronised. In this arrangement the two ignitions will be synchronised when the hand control gets to mid-position. M&B 45° Running positions all synchronised. 45° For switch starting. All this is done ONLY for simplicity of understanding, and less risk of error such as we have found on EAC.7., where the magneto control was a costly error in adjusting the rod lengths. In the magneto fully retarded position it should fire the engine at very slow speed, say 200 revs. or less, but in the advanced position it need not fire until over 1000 revs. because it can never be fully advanced unless the engine is running fast. R.{Sir Henry Royce} | ||