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).
The performance of four different types of 14 m/m sparking plugs on a C.XLII Unit.
| Identifier | ExFiles\Box 162\6\ img135 | |
| Date | 18th April 1932 | |
| FOR FILES. 84485. 18.4.32. X.1918. X.4425. 14 m/m Sparking Plugs on C.XLII Unit. Four different types of 14 m/m Sparking Plugs have been tried on the above unit which has Cast Iron Turbulent Head giving a compression ratio of 6.2:1, extensive tests have not been carried and the results stated are only our impressions after short runs such as for Power Curves etc. The fuel used for the test was B.P. Plus and the types of Plugs were K.L.G.- L.K.1, K.L.G.- S.5., Lodge H.14 and Lodge A.15 (Aero.). K.L.G.- L.K.1. The type of Plug runs very hot so that when the engine is either throttled down or the speed is brought down rapidly at full-throttle the engine cuts right out. K.L.G./S.5. This type of Plug runs much cooler than previous type but slight trouble was experienced with opening up after running at high speed, they are however definitely better than L.K.1 type. The slow running is fairly good but they do not appear to be as good as the three point K.L.G. K.1 type as fitted to standard 20/25 units. Lodge H.14. These plugs are very similar in performance to K.L.G.- S.5., and there appears to be little to chose between the two types, the same trouble was experienced in opening up after running at high speeds. Lodge A.15 (Aero). These plugs gave the best all round performance, they were cool at high speeds and no trouble was experienced in opening up after high speed running. The slow running was perhaps not quite so good as S.5 and H.14 but in every other respect they were definitely better. HS{Lord Ernest Hives - Chair}/R.Mathews. Lec.2924 | ||