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).
Comparative test report on Watford and American Bosch magnetos, including bench and road tests.
| Identifier | ExFiles\Box 4\5\ 05-page064 | |
| Date | 20th July 1920 | |
| -3- HS{Lord Ernest Hives - Chair}5/LG20.7.20. Contd. breaker. It will be seen from the results that the Bosch Magneto gives a slightly better spark than the Watford on the bench. We have, however, carried out comparative tests on the same car and cannot find any difference in the running with the American Bosch compared with the Watford. The new Watford has the advantage that the car can be started up easily by hand or with the starter from cold with the magneto retarded. We think the American Bosch Magneto ZR 6 type could be expected to give good results but we could not, from the short time we have had it, recommend it for immediate standardisation. Particulars. | Watford. | American Bosch. --- | --- | --- Weight. - | 12.8 lbs. | 15. Silence. | V.{VIENNA} Fair. | Good - has advantage of adjustable bearing gear wheel. Lowest speed at which spark would jump 5.5 mm gap retarded. | 190 RPM | 300 RPM. Lowest speed at which spark would jump 5.5 mm gap advanced. | 180 RPM. | 110 RPM. Sparking under pressure Magneto running at 1000 RPM retarded plug gap .020" | Cutout at 100 lbs. | Cutout at 100 lbs. As above - advanced. | 90 lbs. | 80 lbs. Heat test - The spark from the Bosch Magneto is hotter than that from the Watford. Hs.{Lord Ernest Hives - Chair} | ||