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).
Development and testing of ignition system components, comparing them to Delco-Remy and Bosch systems.
| Identifier | ExFiles\Box 35\6\ scan 335 | |
| Date | 10th October 1927 | |
| Contd. -2- EFC4/T6.10.27. certain way. But we have not yet quite got to the final arrangement. This will answer the query contained in your 5th paragraph. That is to say, the most improved development from the point of more efficient running generally, is in the alteration which we shall undoubtedly make in due course to the mechanics of the contact breaker, and when that is right, it does not seem to matter very much reducing the current by using finer primary coils or larger ballast resistances, though we have done this to some extent. When we get the points right it wont particularly matter to reduce the current, as the amount of current saved is almost negligible. We have been through various experiments with various ideas for improving the action of the contact points, such as ventilation, and shielding the contact breaker from the distributor gasses, but nothing seems to affect and improve the action of the contact points appreciably until we begin to mount the fixed contact point in some particular way. Then we can get better results, though not yet consistently as good as the Delco-Remy. It may interest you to know that comparative tests on the U.S.A. Bosch ignition on the same lines show this to be very little better (if any) than our own has been, and not as good as what we have got our own to experimentally at the present time. It is the Delco-Remy which is so consistently good in this respect, and will work with perfect points on any electrical arrangement of our own ignition which we have used. It will also work very much better with platinum points than our own contact breaker. One development which we should mention is the mushroom rotor which, although showing no advantage from the point of view of increasing the life of the points, will have the advantage of additional tracking length, and will almost certainly be standardised from that point of view because there have been one or two failures of the present standard type rotor by the spark tracking along the surface and then jumping across to the metal of the contact breaker casing. It is quite true that we have comparatively recently standardised a finer primary winding coil and also a double value ballast resistance, particulars of which the D.O. will probably give you. But in view of our latest experiences we do not regard these as marked developments. Having proved that they would run the car satisfactorily, it was very largely assumed that because of the reduced current they must give better contact point life, and perhaps this Contd. | ||