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).
Further carburation tests for the Phantom III model, focusing on fuel levels, pumps, and float mechanisms.
| Identifier | ExFiles\Box 93\2\ scan0177 | |
| Date | 14th December 1936 | |
| 308 To Rm.{William Robotham - Chief Engineer} c. to Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} [struck through] Rm{William Robotham - Chief Engineer}/GR.{George Ratcliffe}2/JH.14.12.36. Further tests have been carried out on the Ph.III relative to the report on carburation (1.12.36.). The fuel level in the floatchamber, with the standard layout, is reduced .350" when the maximum demand of 112/pts.hr. is drawn from the floatchamber by adequate drains under the main metering jets. When the ligh lift pumps, mounted in the frame, are used, the reduction is only .150" under identical conditions. As previously reported, an .055" or smaller byepass jet can be used to advantage. With the object of reducing restriction, a 90° needle and an increased diameter of seating from .180" to .212" was tested. The result was only a small improvement of .050" i.e. .300" as against .350" reduction in level, under standard conditions. The seating diameter of .212", is the maximum that can be used with the present detachable seat. The float mechanism was then inspected, and gave a ration of 4.6 : 1. This ratio was reduced to 2.3 : 1 and tested under standard conditions. The result was a decided improvement, and reduction in level of only .130" as compared with .350" at 112 pts/hr. Summary of test results. The alternatives are (1) High lift petrol pumps mounted in the framwp and no alteration to the carburetter floatchamber. (2) Reduction in ratio of float to needle and retain the standard petrol pumps. This necessitates alteration to casting and float mechanism of carburetter. The above tests were carried out in conjunction with Rm{William Robotham - Chief Engineer}/JBD.{John B. Dixon - Fuel Systems} Rm{William Robotham - Chief Engineer}/G.Ratcliffe. [signature] H.Ratcliffe | ||