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).
Performance and selection of ignition plugs for the 40/50 and Goshawk models.
| Identifier | ExFiles\Box 33\3\ Scan220 | |
| Date | 26th September 1922 | |
| X1812 C. BY.{R.W. Bailey - Chief Engineer} c. to Wd.{Mr Wood/Mr Whitehead} c. to Hs.{Lord Ernest Hives - Chair} c. to E.{Mr Elliott - Chief Engineer} EP{G. Eric Platford - Chief Quality Engineer}15/H26.9.22. RECEIVED STAMP: Hs{Lord Ernest Hives - Chair} SFF 29 SEP 1922 re. IGNITION PLUGS. We are now having to turn out our 40/50 chassis with Lodge C.9 plugs in the intermediate position. I pointed out in my EP{G. Eric Platford - Chief Quality Engineer}6/H28.10.21, that this type of plug was not satisfactory for the intermediate position, owing to the tendency to soot or oil up easily, and until we were able to obtain better carburation it was essential that some plug which was less liable to give trouble in this direction, even though it was more inclined to pre-ignite, should be used. The best combination we have had was the Mercury plug for the intermediate and the Lodge C.9 for the pocket position. For the 40/50 car therefore, I recommend that we should still maintain a stock of plugs of the Lodge C.9 type which should be instructed and standardised for use in the pocket position. As we cannot, however, now obtain Mercury Plugs I recommend that the Lodge Steatite Plugs, Model Z.22, which Hs.{Lord Ernest Hives - Chair} reports, is a plug which although inclined to pre-ignite, does not suffer so easily from oiling or sooting up, should be used for the intermediate position. The Mercury plug had this characteristic, and I feel there must be several similar cheap plugs which are the same, and this is a point which might be still further experimented on to advantage. The point I am anxious to make clear at this stage is that the present 40/50 pocket position plug is inclined to pre-ignite, but not oil or soot up, whereas the intermediate position plug does not easily pre-ignite, but is very much inclined to oil or soot up. As regards the ignition plug for the Goshawk car - we have not yet found any plug which is more suitable than the K.L.G. K.1 type. The characteristic of the engine, however, is that the plugs very easily pre-ignite, but the engine does not suffer seriously from over-oiling or sooting up. The only defect appears to be that if the engine is run under load for any length of time, the engine is affected by the slight oiling up of the plugs, which can be easily corrected by cleaning. At the same time, with this type of plug, the heat caused when the engine is run under full throttle conditions cleans these plugs and produces good slow running. CONTD. | ||