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).
Pre-ignition issues caused by over-heated Champion ignition plugs, their failures, and potential design flaws.
| Identifier | WestWitteringFiles\G\September1921\ Scan38 | |
| Date | 9th September 1921 | |
| ORIGINAL 6 To R.R. of America Inc. from R.{Sir Henry Royce} (For the attention of Gr.{George Ratcliffe}) Copy to ~~SGB.~~ HS.{Lord Ernest Hives - Chair} R16/G5/9/21. RECEIVED X4196 X4795 RE IGNITION PLUGS. X 1812? X4305 extract In some of your descriptions you say that with heated pipes, or with certain arrangements of induction pipes you get pre-ignitions. I could not quite understand what you meant by this. I now learn that you refer to pre-ignitions from over-heated plugs. If the Champion plugs you use cause preignitions under any circumstances of our usual running or mixtures, or heat under the bonnet, it shews that these plugs are defective in this respect for our engines, and it is necessary to fit a plug where the insulation gets less hot. My own experience with the Champion plug on another engine is that it caused preignitions and spoilt the power of the engine. This was entirely cured by replacing it with another type of plug in which the porcelain did not get so hot, when the full power was again obtained. Moreover, the Champion plug mentioned soon failed through the little ring of porcelain breaking away and falling down over the points. We believe that the Champion people have another plug in which the electrode is buried in a sort of hemisphere of porcelain. In this case, no doubt, the porcelain would not get so hot as those we have had. Preignitions from over-heated plugs should not occur under any circumstances, and suggest either a defective design or make of plug, or defective cooling of the plug. Personally, I have never experienced this on our car engine, but on aero engines and other cars and stationary engines (Contd.) | ||