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).
The inspection and testing procedures for engine spark plugs.
| Identifier | ExFiles\Box 35\4\ scan 004 | |
| Date | 17th March 1928 guessed | |
| E.E.344. -2- 3. General Inspection of the Plugs. The open end of the plugs was examined and one of the plugs was detached for inspection. The surfaces exposed to the engine gases were found coated with a brownish deposit intermingled with small beads of dull red material. This condition is typical of sparking plugs which have been used in engines running in fuel containing ethyl fluid, the plugs having been subsequently exposed to the atmosphere for a short period. 4. Tests. The following tests were carried out on the plugs:- (a). Measurement of gap between electrodes. (b). Determination of the air pressure (cold) at which sparking ceased. (c). Measurement of the insulation resistance of the plugs by 1,000 volt megger. (d). Measurement of the effective insulation resistance of the plugs at various temperatures. For this purpose a magneto calibrated by means of an artificial leak was used. Sparking at the plug electrodes was suppressed by the application of air pressure. (e). Engine tests on R.A.E. 24 T. air cooled S.C. unit using 20% benzol. The following table shows the results obtained on the six plugs in the condition as received. All the measurements were made at atmospheric temperature. Table/ | ||