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 suitability of U.S.A. Bosch magnetos, comparing radial and flat distributors, and long versus short cams.
| Identifier | WestWitteringFiles\F\February1921\ Scan21 | |
| Date | 10th February 1921 | |
| To-HS.{Lord Ernest Hives - Chair} from R.{Sir Henry Royce} Copy to CE. " " EFC. " " R-R of America. (For attention of CY.) ORIGINAL RECEIVED 16 FEB. 1921 R9/G9/2/21 EFC FEB 10 1921 RECEIVED (4 X 3902 X 3916 RE MAGNETOS - U.S.A. I understand from Mr. Clark's experimental work that the U.S.A. Bosch Company are now making a ZR.6 Magneto which is almost identical with the genuine German Bosch machine. I am not quite sure, however, whether the American Bosch in the ZR.6 retains the flat distributor or whether this model has the radial distributor. My definite advice is that we ought to insist upon the radial distributor, and be sure that these are fitted with suitable carbons, and will not leave a track of carbon dust on the stationary part of the distributor. I do not know any reason for the long or short cam. My own impression is that the short cam is quite good. Apparently there is very little advantage or disadvantage in either. X.3914 Apparently also the B.6 is a jumped spark distributor giving off nitric acid which is apparent during test run. It will be necessary for the U.S.A. Company to see that the workmanship and the guarantee is in order. X.2375 If it is decided to change from the Watford magneto to U.S.A. ZR.6 type for the American cars on your recommendation, this matter must naturally be put through the usual standardisation system, so that we can obtain the signature of everyone interested. R.{Sir Henry Royce} * We found at W.W. that with a long cam the engine would fire backwards (hand starting dangerous) and the engine run backwards until the gas in the exhaust was consumed. | ||