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).
Letter from S.U. Carburetter Co. Ltd. discussing vacuum-controlled ignition and carburetter float chamber tilt angles.
| Identifier | ExFiles\Box 121\3\ scan0099 | |
| Date | 3rd December 1940 guessed | |
| THE S.U. CARBURETTER CO. LTD. CONTINUATION No. 3. W. A.{Mr Adams} Robotham, Esq., DERBY. The scheme we originally intended to use, had we come to the conclusion that the gain would have justified it, was to use vacuum controlled ignition, and to use this as a control valve for the depression above the piston rod. One of the advantages in doing this is that the additional advance and the weakening come in simultaneously, as they should. As regards your last paragraph, the tilt which can be permitted depends on what modifications are made to the float chamber; we can quite well work on a lower level, the only disadvantage in doing this is that starting may not be quite so good, owing to the depression, under these conditions, being in-sufficient to lift the petrol through the greater height. Actually this can be overcome by flooding the carburetter, which might be permissible on a tank. The effect of the low level on the mixture supplied with the S.U. is practically negligible. The standard carburetter and float chamber would stand quite a severe angle/tilt, even 45°, under running conditions, but if it were left standing at this angle flooding into the choke might occur. We think, therefore, the best way of tackling this is for you to tell us what angle you want to run at, and what angle you want to park at, it will then be possible to judge what alter-ations are necessary to comply with these conditions. Tilting the carburetter may have some weakening effect owing to the vertical component of the weight of the piston being reduced, but this, should it be found to be detrimental, could be overcome by using a lighter piston and spring. Yours faithfully, for THE S. U. CARBURETTER CO. LTD. T Leslie Kent | ||