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).
Specifications for a new experimental production car's ignition system.
| Identifier | ExFiles\Box 181\M11\ img135 | |
| Date | 1st February 1919 | |
| To EFC. from R.{Sir Henry Royce} Copy to CJ. ORIGINAL X.3129 RE PRODUCTION CAR IGNITION. It is imperative that the new experimental chassis be fitted with exactly the ignition that is intended to be used for production. I have the impression that we shall be able to make the ignition fire satisfactorily with a make and break ratio of one to one, i.e. .5 make. This, of course, would be the best proportion for the old pattern contact maker and present cam. I think you will find that if this is done, and the high tension distributor is made as we have already arranged it, to only just arrive at the proper cylinder at the time the break takes place, and have a trailing edge to the contact long enough to favour the ignition in running backwards to fire the cylinder which would nominally be past the centre, that is, it would appear to me that with the six-cylinder ignition the make and break would each be 30°, so that the distributor would be 30° late after the break took place in the make position. This appears to be sufficient to induce the spark to travel to the cylinder, in which it would do no harm as far as running backwards is concerned. I would like you to take the matter up with Mr. Hives, and Mr. Platford, as to whether this ignition will run the engine as satisfactorily slow running, as the old trembler ignition. The reason I ask this is that the 7 CA which we have here appears to run badly at slow speed. It may be that the plugs are not in the best condition for slow running, or that (Contd.) | ||