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 testing of EW6 magnetos for noise issues, detailing the causes and results from experimental machines.
| Identifier | WestWitteringFiles\R\2December1927-February1928\ Scan173 | |
| Date | 13th December 1927 | |
| -2- Contd. these machines back to alter the cams in accordance with our suggestions. Since the time of writing EFC6/T13.12.27 in which reference was made to the EW6 magneto. No.100080 on 14-EX which you have, and to magneto No.100081 which has been fitted to Sports chassis 15-EX (which we understand has been brought to you), we have received through this Expl.) Dept. a further six magnetos of this type, and yet a further nine have been passed to Mr. Ellis for production test (which we have specified). Altogether the results of these machines are not completely satisfactory. Of the six experimental machines, four have been tried for noise by our testers on an expl. car and the report is as follows :- "We have tested the four magnetos which you handed to us with the following results, only one of these (No.100094) was considered acceptable with regard to quietness as compared with the present EC6 Type. The make and break noise is the chief complaint although two of the magnetos tested had squeaky H.T. distributor brushes. It was found that in the present design the magnitude of the noise depended upon the following causes:- (1) Size of gap between contact points. (2) Strength of contact breaker spring. (3) Bedding of contact points. In (1) it was found that the size of the gap between the contact points of the EW6 type magneto No.99802 fitted to 9-EX 31.10.27 (3168 miles) had increased from .012 to .025". In case (3), if the contact points were only touching on one edge at the magneto was considerably quieter. We also found that the fitting of the cam sleeve varied, making it impossible for the return spring to retard the magneto in one case (100094). Contd. | ||