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).
Causes of harsh engines, attributing the issue to overly advanced ignition timing.
| Identifier | ExFiles\Box 37\1\ scan 234 | |
| Date | 18th October 1922 | |
| TO Hs{Lord Ernest Hives - Chair} EP{G. Eric Platford - Chief Quality Engineer} } from R.{Sir Henry Royce} OY PN{Mr Northey} } CJ BJ } X.3949 R3/M18.10.22. HARSH ENGINES - X.4219 X.928 X.3949 I shall be pleased if Mr. Hives and Mr. Platford will on every possible occasion find out whether my impressions are correct that most of the harsh engines are caused by the ignition being too early. In the case of the 40/50 it would apply probably to the magneto, of which the range of advance is not very great. Many drivers would run with the ignition unnecessarily advanced and constantly advanced so that the timing was definitely wrong at slow speeds. Many drivers would also run well advanced and imagine they got more power because they felt the engine more. Unfortunately the power does not fall off very quickly with an engine the ignition of which is too early, but on the other hand undoubtedly the smooth running of the engine varies tremendously with the timing. You will therefore see that it is possible to get good acceleration and powerful running with the ignition too far advanced for the sweet running of the engine. I believe it will be found that this has more influence than the slight changes of compression, and that a high compression engine with slightly later ignition would be equally smooth and a better engine than a low compression with somewhat too early advance. This impression I have gathered from No.6 Goshawk, the smoothness of which has been absolutely ruined by a slight increase in advance, and tremendously improved by a slight decrease in the advance from the position as received from Derby, which one imagines on this engine was earlier than No.4. Goshawk. In this particular case contd:- | ||