Letter regarding pre-ignition issues with ignition plugs and the successful testing of new Champion plugs.
| Identifier | ExFiles\Box 33\3\ Scan168 | |
| Date | 20th September 1921 | |
| Oyl - G 20981 X1812 b. Sept. 20, 1921 RECEIVED STAMP: W.G. 4 OCT 1921 Mr. Claude Johnson, Managing Director, Rolls-Royce Ltd., London, England. Attention: Messrs. Royce & Hives. Dear Sir:- Re: Ignition Plugs Replying to Mr. Royce's letter R16/G5/9/21 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 does not 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 detonation. 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 to 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 Handwritten References: X1812 X4196 X4305 | ||
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).