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).
Test report detailing modifications and observations of a large capacity centre chamber's effect on fuel mixture.
| Identifier | ExFiles\Box 93\2\ scan0056 | |
| Date | 8th July 1938 | |
| -7- Rs{Sir Henry Royce's Secretary}/CTS{C. Trot Salt - Carburation};16/KW. 8.7.38. Test No. 9. EX.1831C. (Large Capacity Centre Chamber). Object. To deal with unvaporised fuel as soon as it leaves the riser, and to change its condition before entering the main pipe. Fig.14. Test 'A'. A window was placed in the side of the centre chamber, so that the heavy mixture could actually be seen, passing from the riser to the main pipe. Result. It was clear straight away that the heavy drops of petrol which collected at tick-over speeds at the end of the riser, were upsetting the quality of slow running. It was also surprising that at tick-over speeds the water hot-spot at the base of the chamber only was quite sufficient to deal with all the unvaporised fuel which collected there. At low speeds full throttle, however, it was very surprising to see the actual amount of petrol being swirled about in this chamber. The swirl was most noticeable at half throttle (throttle bias). This was proved by turning the carburetter round, the swirl going in the opposite direction. Slow Running: 10% improvement over Test No. 3 (downdraught). Pick Up: Fair. Distribution: Good over whole range. Fig.15. Test 'B'. Object. To eliminate throttle bias, and ascertain the value of "swirl". This lowered ceiling was first left with a sharp edge. Results. Apart from the fact that one could see through the window that throttle bias was not so pronounced, there were no outward signs of any difference in running. After putting a generous radius to this lowered ceiling (Fig.1b), a slight improvement showed in tick-over. The wet petrol coming down the riser was running partly round this radius before coming away, and a | ||