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 discussing ignition plug pre-ignition issues and the performance of Champion plugs on dynamometer tests.
| Identifier | ExFiles\Box 35\3\ scan 150 | |
| Date | 20th September 1921 | |
| X4196 OY1/G20.9.21. Mr. Claude Johnson, Managing Director, Rolls-Royce Ltd., London, England. Attention - Messrs. Royce and Hives. Dear Sir, RE. IGNITION PLUGS. X1812. X4196 - X.4305 Replying to Mr. Royce's letter R16/H5.9.21 on this subject. In the one case in which we heated the induction pipe at the Tee, we most certainly got pre-ignitions, which presumably could only have proceeded from the hot porcelains of the ignition plugs. This trouble doesnot occur, however, under ordinary conditions - it was only due to the excessive temperatures in the induction pipes. That these were actually pre-ignitions which we obtained is proved, we think, by the very high temperature indicated by a yellow deposit of chromium oxide on the surface of the exhaust valves. It was certainly not a case of ordinary detonations. As stated, above, the Champion plugs do not cause pre-ignition, even on dynamometer tests. In fact, the new type of Champion plug with petticoat porcelain, referred to in Mr. Royce's letter, is designed with the idea of obtaining a higher temperature on the porcelain to burn off accumulated carbon, and we have proved that we can use this plug successfully on the dynamometer without pre-ignition. I think Mr. Royce will agree that if we find the Champion plugs will stand up on dynamometer conditions without pre-igniting and will also stand up to road conditions without fouling, they should be regarded as satisfactory for use on the car. Yours truly, ROLLS-ROYCE OF AMERICA, Inc. per. M.{Mr Moon / Mr Moore} Olley. MO/G.{Mr Griffiths - Chief Accountant / Mr Gnapp} | ||