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).
Ignition system failings and potential improvements for the 40/50 model.
| Identifier | ExFiles\Box 54\5\ Scan172 | |
| Date | 29th December 1921 | |
| contd:- -2- EPC2/LG29.12.21. Apparently the only failing of the 40/50 ignition as regards the quantities involved e.g., voltages, resistance, and inductances, exist during starting up from cold when the battery voltage may be comparatively low. This, of course, is partly a failing of the battery which will latterly be a little more pronounced owing to the introduction of the ebonite separators which it has been necessary to effect in order to secure reliability. It is likely that a battery of 25% more capacity would prevent this occurring. We understand that the Sales Dept. are strongly urging the use of a larger battery for the 40/50 H.P. for several reasons, which perhaps include this. At the time of starting up, the ignition coil current can be increased sufficiently to effect starting by cutting out part, or all, of the ballast resistance; it is the time when nearly all the conditions of the ignition are unfavourable. We give this merely as a suggestion that if the push button switch were made as a 3-point switch, a wire from the new switching point could be carried to that end of the ballast resistance adjacent to the coil primary so that at the time of starting up the ballast resistance would automatically be taken out of the circuit and the start made more certain on a cold morning as regards ignition. We have from time to time given quite a lot of thought to battery ignition problems and have attempted to arrive mathematically at some knowledge as to what actually occurs, but when all the facts present are included and considering that the whole problem of ignition is bound up with that of carburation and sparking plugs, it is really very difficult to come to any contd:- | ||