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).
24-hour test of a new sparking plug design for the 'Eagle' 'B' engine, comparing it to a Bosch model.
| Identifier | ExFiles\Box 34\3\ Scan003 | |
| Date | 8th September 1916 | |
| R.R. 255 a (400) T. (S.C. 836 18-2-16) G.{Mr Griffiths - Chief Accountant / Mr Gnapp} 1548. To R.{Sir Henry Royce} from EH. c. to J.{Mr Johnson W.M.} c. to Ne. c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to Ey. c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} EHL/D8916. September 8th 1916. Extract from "EAGLE" "B" ENGINE. X.2246 X.No. X.2246 This long test was run on sparking plugs which we made ourselves from som four pointed Bosch. This test is far and away the best record we have ever hadwith any plugs; the engine ran for 24 hours without changing one and there were no signs ofpre-ignitions during the run. The original four pointed Bosch will notrun in our engine because the points drop off. We took some of the centre electrodes which had the points drop off and altered them like the model plug we are sending Mr. Royce. We tried som plugs with a centre stem which gave one single point, but these misfired after a few hours'running. We think that why this plug has been so successful is because the centre electrode is much less exposed to the heat (we know that it is the centre electrode which gives all the trouble with pre-ignitions); any points which are fixed to the body of the plug will always keep cool. Also we do not rely on a single point giving a long length of gap for the spark to jump across. The fact that the spark takes place in a pocket might also help to keep it cool. [Handwritten in left margin]: 2/100 | ||