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).
Suitability of Lodge mica ignition plugs compared to porcelain and K.L.G. types.
| Identifier | ExFiles\Box 33\3\ Scan078 | |
| Date | 10th September 1920 | |
| To Hs.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} Copy to CJ. " " Bn.{W.O. Bentley / Mr Barrington} " " Da.{Bernard Day - Chassis Design} " " By.{R.W. Bailey - Chief Engineer} " " EFC. " " EP.{G. Eric Platford - Chief Quality Engineer} " " Oy. X 1812 l R5/G10.9.20. X.1812. RE IGNITION PLUG. X.1918. X.3413. X.2635. On looking over the spares in 6.EX and 1.EX I find the Ignition plugs we appear now to be sending out with are Lodge make/the internal insulation of mica. I am not sure that these plugs are the most satisfactory that can be used. You will remember that directly after the War we had a lot of trouble with K.L.G. mica plugs because of the surface insulation gradually accumulating soot. A slight amount is often generated during starting, especially in cold weather. We then came to the conclusion that the porcelain plug in which the insulation (stoneware or porcelain) was on the lines of the old Pognon plugs, the walls standing around the electrode giving an internal and external surface of insulation, and in which the wall got hot and burnt off any soot that may have accumulated before it became a definite conductor. It may be that these present Lodge plugs are the result of the difficulty of getting such a wall of porcelain or stoneware to stand the heat without breaking, and also it may be that the mica used in the way of the present Lodge plug is quite satisfactory owing to the central electrode getting hot enough to allow the mica to burn off the carbon deposit. Contd. | ||