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).
Misfiring issues, recommending specific magnetos and discussing tests on different spark plugs and ignition coils.
| Identifier | ExFiles\Box 4\5\ 05-page193 | |
| Date | 1st May 1921 | |
| Contd. -7- Hsl/LGS.5.21. it is liable to give us misfiring under full throttle weak mixture conditions. In future, however, we recommend that any magnetos we get from the Watford Company shall be the EO6 type and that if we can, we should exchange the E6 type magneto which we have in stock to the EO6 type. This will be an improvement but we still think, however, that we need a larger magneto. It will give us a greater margin of safety. The safety spark gap on a magneto, we consider, should be 10 mm. (.400"). Perhaps one of the chief reasons why we need a larger magneto is because of the difference in sparking plugs. We have proved on the car that the Mercury plugs are liable to cause missing fire picking up with a weak mixture with the Watford magneto. It is because the resistance at the plug points appears to be higher than on the standard Lodge plugs. If we fit a Bosch magneto the trouble practically disappears. We shall be sending a separate report as regards the tests we are making on plugs. So far our tests shew that plugs which are good for not sooting up, such as Mercury and Champion, are bad for resistance - the bigger margin we have on the magneto, the less exacting are our plug requirements. During these tests we have carried out tests on the coils. We have tried coils with 14,000, 16,000 and 18,000 turns on the secondary instead of the standard 21,000. We find that the coils with less turns on the secondary gave the worst results. If we fix the safety spark gap in the coil ignition, the same as on the Watford magneto, we get a very similar results. Hs.{Lord Ernest Hives - Chair} | ||