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).
Summary page discussing irreversible changes in spark plug conductivity and proposing further engine tests.
| Identifier | ExFiles\Box 35\4\ scan 002 | |
| Date | 17th March 1928 guessed | |
| E.E.344. (Summary). 2. conductivity very rapidly and assume insulation values comparable to those given by new plugs. (d). This change, which was found to be irreversible and permanent in character, may be due to disintegration of the deposit on the porcelain insulator arising from possible differences in the relative co-efficients of expansion of the two substances, or to a chemical change in the nature of the deposit itself at a critical temperature. (e). The data obtained from this investigation is regarded as of considerable importance particularly in relation to the operation of porcelain insulated plugs on engines using doped fuel. (f). It is suggested that a similar type of plug designed to run slightly hotter at the lower end of the scale but still outside the range of pre-ignition should be tried in the Falcon XI engine. 4. Further Developments. (a). Engine tests will be made with plugs which run at a higher insulation temperature. (b). If such hotter types of plugs still exhibit the same phenomenon a complete analysis should be made of the temperature resistance characteristics of the deposits. ---------------------- | ||