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 investigation into the noisiness of Watford EW6 magnetos using modified cams.
| Identifier | ExFiles\Box 40\2\ Scan239 | |
| Date | 11th February 1928 | |
| To R.{Sir Henry Royce} from EFC. c. BJ. E.{Mr Elliott - Chief Engineer} c. Da.{Bernard Day - Chassis Design} Ev.{Ivan Evernden - coachwork} c. Wor.{Arthur Wormald - General Works Manager} X8793 EFC1/T11.2.28. WATFORD EW6 MAGNETOS. X7791 In our last report EFC6/T13.12.27, we stated that we were pursuing the question of noisiness of the make and break by the use of modified cams. We received from Messrs. North some short cams supposed to be produced to our requirements of easier make (but not suitable for electrical functioning of the magneto). These were tried for noise both on the bench and on a car, and we considered that they showed some improvement. We have not been able to persuade Messrs. North to give us on the EW6 magnetos which we have recently received, cams giving the right make ratio and at the same time the easier make. We specified to them that whereas the instant of break should be altered not more than ± 3º to correspond to an alteration in the gap of ± .004", in the case of the make the variation in the angle might be ± 10º to correspond to the same ± .004" in the gap. All magnetos received so far have, as far as we can see or have tested, the same rate of make as break. During their visit to us on the 8th inst. they said the reason they had not given us this was that they had themselves tried it and did not consider it would be any advantage. We think that most of the noise occurs at make and we know that electrically it does not matter seriously if a wide variation of make point takes place due to variation of gap. Owing to the fact that the magnetos we have received are still mostly noisy, they have agreed to take a number of Contd. | ||