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).
Design and performance of different types of spark plugs, specifically comparing mica and pot insulation.
| Identifier | ExFiles\Box 79\1\ scan0062 | |
| Date | 12th October 1912 | |
| /EH5/L91115. 2. metal on the centre stem, their idea is that this thick portion of the stem is only separated from the plug body by a wrapping of mica and that the heat will be conducted through the mica to the body.. This arrangement necessitates mica insulations. They admit that mica plugs will not stand oil and that the life of a mica plug is much shorter than one with a pot insulation. The Lodge people have never experienced the trouble we had with single point plugs missing fire, although they appreciate the extra resistance in an outside spark gap due to the points oxidizing. There is no doubt that the plug we want should have if possible pot insulation and multi points. On another Lodge plug which was pre-ignited we tried a large copper radiator, this did not prevent pre-ignitions. E.H. K K 339 V (200 B) (2'B 30' 12-10-12) C 1313 | ||