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).
Engine distributor and contact breaker troubles at high speeds.
| Identifier | ExFiles\Box 36\3\ scan 030 | |
| Date | 15th February 1916 | |
| R.R. A.{Mr Adams} 398 (400 T.) (S.C. 536. 15-2-16) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1546. -3- Contd. X.2823 Since writing the foregoing I have received your further report of the troubles you have experienced when using the high speed contact breaker on the engine. There is little doubt that this is entirely a question of distributor troubles. The distributor has much to do owing to the rapidity with which the sparks follow one another. The gaps on the distributor are not sufficiently open. A distributor on an engine is working under entirely different conditions to those on the bench test, owing to the enormous difference in the reistance of the path of the spark between the cylinder under compression and the one immediately before it, ehich is still in/a somewhat uncompressed state, as realised in your note. The contacts would be much nearer together in the case of our 12,000 sparks oer minute. We experienced this trouble with the Rolls-Royce battery ignition distributor. It was found that the centrifugal force of the carbon block caused considerable wear of the carbon, coating the inside of the distributor with carbon dust. This was considerably improved by using stationary carbon brushes instead of a revolving one. It was not finally overcome, however, until we adopted a jump spark distributor. It would appear, therefore, that the system of firing so may cylinders at so high a speed, will demand a very perfect distributor. If the carbon revolves, it would be a slow speed one, and at least doubel pole. It would not definitely overcome the trouble by putting the sparking points of the ignition plugs nearer together. As far as the contact maker is concerned, I do not think this is the cause of the trouble, providing you put sufficient | ||