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).
Test report on sparking plug performance on experimental Phantom II and production 20/25 chassis.
| Identifier | ExFiles\Box 37\1\ scan 186 | |
| Date | 5th December 1930 guessed | |
| W.E. 63 (2) Contd. on experimental Phantom II chassis 19EX with standard compression ratio 4.6 to 1 and with the sparking plug gaps set at .025" and at .030" (.025" standard setting), also with standard KLG type K1 plugs on a production 20/25 chassis from the Test Dept (Compression ratio 5.25 to 1) in this instance with the plug gaps set at .020" and at .030" (.020" standard setting). The engine cooling water temperature in each case was maintained at approximately 70°C but in the case of chassis 19EX an additional test was made with the plugs very hot, the engine being warmed up by allowing the cooling water temperature to be maintained at boiling point for half an hour. The results obtained are set out as follows:- Phantom II chassis 19EX. @ Plug gaps .025" Water temp 70°C Cylinder NO | Plug voltage 1 | 4820 2 | 5050 3 | 6300 | ||