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).
Distributor make ratio and ignition timing, with a supporting diagram.
| Identifier | Morton\M11\ img137 | |
| Date | 30th April 1921 | |
| To EFC. from R.{Sir Henry Royce} -3- R4/G1219 Contd. My scheme is that the make ratio is made as large as convenient, and assuming that the distributor moves exactly with the low tension timer, and that the distributor is always fitted in relation to the timer as late as possible, and has a one to one duration, then in moving backwards the apparatus can only fire a cylinder that is past. [Diagram showing firing order and duration] Diagram annotations: No1, *4, *2, 6, 3*, 5*, duration 30°. Text next to diagram: Position of distributor rotor when firing No.1 normally. Then moving backwards ignition has no chance of firing 1 but will fire 4. This will be safer the longer the make period, not the shorter as stated in your memo. R.{Sir Henry Royce} [illegible signature] [Faint text at bottom left: W H & S Ltd (200 J) (S.D. 408 30-4-21) D W S1201?] | ||