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).
Results of engine performance tests using different spark plugs and tappet settings.
| Identifier | ExFiles\Box 162\4\ img007 | |
| Date | 31th May 1933 guessed | |
| -2- Lodge X.306 Reach .550 Pick up good at first but deteriorated with use. Slow running 5 m.p.h. Idling lumpy. All the above tests were carried out with tappets set, Inlet .004, Exhaust .004. The slow running and idling can be improved considerably however, if the Inlet and Exhaust tappets are set at .020 and using either KLG.765 or Lodge X.335 type of plug. The minimum slow running speed with this tappet setting and using either of the plugs mentioned is approximately 3 m.p.h. and quite steady. R.{Sir Henry Royce} Matthews. | ||