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 on a Downdraught Stromberg Carburetter and manifold, detailing faults with fuel loading and low-speed acceleration.
| Identifier | ExFiles\Box 122\1\ scan0186 | |
| Date | 27th May 1935 | |
| To Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} c. to Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation} X033 Hs{Lord Ernest Hives - Chair}/GR.{George Ratcliffe}9/KW.27.5.35. 18-C-IV. Downdraught Stromberg Carburetter with Central Water Heated Floor Manifold. Further tests carried out show the main fault with this manifold is loading up part throttle. At full throttle the centre floor is only subject to a very low depression. This allows wet spirit to collect at the base. Immediately the throttle is partly closed, thus increasing the depression, the loaded fuel is picked up and enters the ports in heavy charges. This would be cured to a great extent by applying greater heat to vaporise at the floor. By reducing the capacity to almost the same bore we lose the advantage of good slow running, but cure the loading up trouble by increasing the depression at this point. Further tests shewed a fault with the carburetter at low speed acceleration, part and full throttle openings. This occurs between 5 and 10 m.p.h. on a fairly steep gradient in top gear. The low speed supply cuts out before the main feed comes into action under the above condition. The low speed supply hole in throttle bore was increased from .050" to .075" in order to prolong the duration. Tests showed no appreciable difference. The air feed or balance hole was then increased from .050" to .062" in order to increase the supply orifice. This gave a finer adjustment of the mixture, but shewed no improvement in the changeover. | ||