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).
Letter from an Engineer Superintendent discussing sparking plug oiling and an experiment to diagnose the cause.
| Identifier | ExFiles\Box 58\2\ Scan267 | |
| Date | 9th December 1935 | |
| IMPERIAL AIRWAYS LTD. -2- CONTINUATION No. ES/JWS/MOD/11,140. 9 December 1935 position of the sparking plug hole, which, in some engines, serves as a sump for the surplus oil on the cylinder walls. I have often thought that the designer of the engines spends much time on the shape of the combustion head, position of valves, etc. and then, as an after thought, puts the sparking plug hole anywhere, completely forgetting oil drainage, propagation of flame, etc., but possibly I am libelling the designer without knowing all the circumstances. As a proof of this, I will tell you of an experiment we carried out fairly recently - an adaptor was made, which screwed into the sparking plug hole and projected beyond the inside level of the sparking plug hole so that no oil could drain into the screwed hole of the adaptor taking the plug. As soon as we found a "Wizard" plug oiling up we removed this plug and fitted the adaptor with its plug. This plug did not oil up on service. We then removed the adaptor and the plug oiled up again. We repeated this experiment until we were satisfied that the oiling up was not the fault of the plug but that of the piston rings. I think the foregoing answers your questions but, if there are any points which I, as a Maintenance Engineer, can write you, as the Designer, I shall be only too pleased and please do not hesitate to write. Yours sincerely, J.W. STIRLING Engineer Superintendent | ||