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).
Comparing different ignition contact point systems and the performance of platinum versus tungsten points.
| Identifier | ExFiles\Box 163\7\ img104 | |
| Date | 31th August 1927 | |
| X4284 To R.{Sir Henry Royce} from EFC. c.c. BJ. Wor.{Arthur Wormald - General Works Manager} c.c. EY. EFCL/T31.8.27. IGNITION CONTACT POINTS. X.2894. X.4652. X.4275. X.4284. Flexible copper connections giving as completely continuous a metallic connection as possible between contact points and condenser foils were experimented upon sometime back and the conclusion was arrived at that there was little or no improvement in the running of the points. Delco-Remy has no such connection but relies upon lever spring and pivot only. U.S.A. Bosch use a small copper strip connector supplementary to the spring. Our experiments have shown that the U.S.A. Bosch is only slightly superior, if at all, to our own. The experiment running at present of U.S.A. Bosch running with the RR. electrical system is going very little better than an ordinary tungsten point test on our own system. They are not going anything like as well as the Delco-Remy. We will examine the question of the characteristics of the current as affected by resistance of the contacts or connections, or bouncing of the contact, comparing in the first instance, our own contact breaker system with Delco-Remy. Delco-Remy lever on RR. contact breaker is running a good deal better than RR. lever, but not as perfectly good as in its own case. The main difference between this arrangement and the complete Remy would appear to be that our contact point screw support, which at the moment carries the Remy screw point, is somewhat more rigid than the Remy screw point carrier. In regard to the question of standardising the tungsten points, the position, apart from the fact of the relative cheapness of tungsten, would appear to be as follows:- (1) Both standard platinum and tungsten points require, to prevent misfiring, trimming once or twice in 10,000 miles (this is supposing that oil vapour is effectively excluded) and in this respect of the frequency of attention, tungsten does not score. (2) The amount of disturbance to the surface is greater with platinum than with tungsten, consequently tungsten will give a longer life. Contd. | ||