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).
Carburetter remedies and development considerations by the S.U. Co., focusing on piston lift and component sizing.
| Identifier | ExFiles\Box 31\5\ Scan155 | |
| Date | 16th April 1934 guessed | |
| -2- This is also aggravated by the sudden jump which the piston gives when the throttle is snapped open. A remedy applied by the S.U. Co. was to do away with the initial lift of the piston, and so have the effect of a normal carburetter, at the same time fitting a cork gland, which shuts off the fuel from the main jet when the piston is resting on the bridge. As this did not seem to them a practical proposition without further development, and owing to the fact that they had spent considerable time on it already, the job was not pursued further than that. However, they suggest various means of overcoming the difficulty, such as the use of a larger low speed choke, with no initial piston lift. From the point of view of pick-up, the S.U. Co. attach more importance to the development of the air valve piston; taking into consideration weight and clearance in the vacuum chamber, both with a view to cutting out the initial flip or jump. The point of actual size of carburetter for a given engine was considered, and although the S.U. Co. state that due to the fully expanding virtues of their carb. a fairly large margin may be allowed for variation in carb. capacity without loss or gain from the engine, the point for maximum depn. in the induction system should be in the carb. In our case, owing to the restriction set up by the passage through the block, the depression on the induction pipe side of the engine is higher than on the carb. side. C.T. Salt. | ||