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).
Engine misfiring issues with weak fuel mixtures and recommendations for magneto improvements.
| Identifier | ExFiles\Box 4\5\ 05-page192 | |
| Date | 1st May 1921 | |
| Hsl/LGS.5.21. -6- Contd. If, when running with a weak mixture full throttle, the whole set of sparking plugs misfired, it would not be very serious. The driver would not be able to appreciate whether it was an ignition miss or a mixture miss but owing to the fact that we get stronger sparks from one side of the magneto we get three cylinders which will fire fairly vigorously and three that will miss. We have confirmed this point on the car. We can run with quite wide gaps on the three cylinders firing with the central electrode negative, but if we change over and put them on the positive side, the missing fire is chonic. The fact of us having a mixture control on the steering column, which we expect drivers to use frequently, impress very severe conditions on to our ignition equipment. It will be seen in the figures we have given that at full power firing the charge at the normal mixture and ignition timing, the resistance of the sparking plug is comparatively small- it increases about four times when we run with a very weak mixture. Another point in connection with this that we realize, is that the worst condition for missing fire is sudden acceleration with a weak mixture. We proved this is a very bad condition. We believe that owing to inertia effects, the first charges in the cylinder are very weak. Recommendations. During our tests we proved that the Watford E06 magneto (sleeve type) is an improvement over the standard E6 type magneto as regards slow running but owing to the fact that the safety spark gap is the same as on the E6 (.300") | ||