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).
Ignition plug performance and lubrication issues on the 6.EX car.
| Identifier | ExFiles\Box 50\2\ Scan068 | |
| Date | 18th October 1921 | |
| To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} c. to CJ. c. to PN.{Mr Northey} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to Hm.{Capt. W. Hallam - Head Repairs} X4295 R1/G18.10.21. X.3923 X.4295 RE IGNITION PLUGS AND LUBRICATION ON 6.EX CAR. X.4337 X.1026 X.4400 The Mercury plugs on this car have done remarkably well, after 3000 miles they are very clean generally, and the porcelains are as clean as when first fitted. They shew no signs of distress through over-heating, but I am not sure that they do not cause pre-ignitions and increase the tendency to detonations by pre-ignitions. I was therefore fitting in place of them, the Sphinx plug which I have tested for pre-ignitions in my little pump engine, but I find on examination that the dimensions and proportions of these Sphinx plugs are identical with those of the Mercury plugs, and I should therefore expect the result to be equal, unless the materials or something I cannot see is different. I would like you to let me know your own experinece in the direction of whether a hot working plug, such as the Mercury, tends to make one think that the engine is pre-igniting or detonating worse than with a cooler working plug. As regards lubricating 6.EX, nothing is done to this for 1,000 mile spells. In such time the engine lubricating oil should be getting low, and is best completely emptied out and refilled with clean new oil. On examining the back axle, it was found that this was flooding at the filler, shewing that it had probably not lost any oil. On lubricating the universal joint, it was found that only a small entrance hole for this oil is provided. This, I think, contd:- | ||