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).
Issues with Lodge mica ignition plugs compared to earlier porcelain types.
| Identifier | WestWitteringFiles\E\September1920\ Scan12 | |
| Date | 1st September 1920 | |
| To HS.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} Copy to Sd. " " BW. " " DA.{Bernard Day - Chassis Design} " " BY.{R.W. Bailey - Chief Engineer} " " EPC. Ex. X.1812 X.3413 ORIGINAL. RE IGNITION PLUG. X.1918 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 are Lodge make with the internal insulation of mica. I am not <u>sure</u> 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. If you examine these plugs you will find that they are extremely difficult to clean, and one does not know when they are clean. This is a very different matter with the detachable | ||