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).
Letter to Messrs. North & Sons Ltd. regarding cold-start issues with EW.6 magnetos and requesting primary winding specifications.
| Identifier | ExFiles\Box 65\3\ scan0235 | |
| Date | 27th March 1928 | |
| X7791 C. Mx.{John H Maddocks - Chief Proving Officer} C. Ry. EFC2/T. 27th March, 1928. Messrs. North & Sons Ltd., Whippendell Road, WATFORD. X8790 X7791 Dear Sirs, Owing to the fact that some of the EW.6. magnetos have not been able to start the engine cold, we have altered our General Specification of Performance of Six Cylinder Magneto (without automatic advance) for R.R. 40/50 H.P. Car, in respect of clauses (5) and (7), and we now send you copy of the revised Specification. (dated 27.3.28) The E.O.6. sleeve type magnetos would pass the low speed test with a considerable margin, but owing to the fact that these EW.6. magnetos would only pass with very little margin, and that now it has been found that some of them will not start the engine cold, we have arrived at the fact that the Specification should be altered in the manner given by the present modification. Presumably you have made experiments on the relative proportion of primary to secondary winding space, but as we have noted that the product of primary U.C. volts x S.C. amperes, each at 400 R.P.M., is less in these magnetos than in the sleeve type, and a good deal less than in the Lucas machine, it occurred to us to query as to whether you have allowed sufficient winding space for the primary winding. In order to make a comparison, we should be pleased if you could let us know the number of primary turns and gauge of wire used. Yours faithfully, FOR ROLLS-ROYCE LIMITED. Specn. X8790 | ||