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).
The design and performance of ignition system components including coils, condensers, distributors, and insulation.
| Identifier | WestWitteringFiles\W\May1931-August1931\ Scan038 | |
| Date | 1st May 1931 | |
| HE/HEM/ADSC.5.31 contd. -2- Ignition Coils. We have now a very satisfactory design of coil which has not given us any trouble in service. We have got to anticipate, however, that as we raise the compression, which we are likely to do on our engines, we have nothing to spare on the ignition coil. At the present time on the 20/25 we run with .020" spark plug gap which is the minimum we can use to obtain good slow running. In service the spark plug points burn away and then have trouble with misfiring. As it is intended to rely solely on the battery ignition, we must make certain that this is always in 100% condition. We have in hand a new design of coil instructed by Ry. to D.Sch.419. This coil is the type which is now used by most makers, which has the primary winding on the outside. With this type of coil the ballast resistance is not used. To get the best results it would appear that we should have to adopt a contact breaker similar to Delco which has a three lobed cam and two levers. The reason for this is because a longer make ratio is required owing to the increased inductance. Having the two contacts should increase the life of the contact breaker. Condenser. Our present condenser is difficult to produce and owing to the fact that it has to be squashed into shape we frequently have complaints of the capacity altering with cars in service. The more usual design used on Delco etc. is a circular type which is very simple to produce. H.T. Distributor. We consider the high tension distributor could be made simpler without loss of efficiency, also the jump in the distributor from the base to the sparking points should be increased because on the 25 HP. we get jumping at this point if the plug points become wide. Insulation. We are continually carrying out tests with the object of improving the quality at reduced cost of both moulded bakelite and sheet bakelite material. With regard to the latter, we are of the opinion that synthetic paper based material is as good for our low voltage conditions as the more expensive linen based material. | ||