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).
Preliminary test results and identified faults for a Phantom III Stromberg Carburetter.
| Identifier | ExFiles\Box 20\9\ Scan120 | |
| Date | 24th February 1936 | |
| To E.{Mr Elliott - Chief Engineer} c. to Wcr. c. to By.{R.W. Bailey - Chief Engineer} c. to Sft.{Mr Swift} X 1033 Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}7/KW.24.2.36. Phantom III Stromberg Carburetter. Preliminary tests have been taken on the test bed with the above carburetter as made by R.R. for production; that is, with R.R. air intake bend, throttle body, controls and other detail alterations. The general power and distribution is unaltered from that obtained with the complete Stromberg produced carburetter. Tests were taken without an air intake silencer as this is not yet available. Several faults, however, were found with the carburetter and are as follows :- (1) The slow running mixture setting could not be weakened off sufficiently. Investigation of this showed that the atmospheric release holes were not drilled centrally and with the throttle in the slow running position, mixture was being drawn from both holes. Comparing with a Stromberg made throttle body, the atmospheric release holes are .075" too near the suction side of the throttle. (2) Accelerator pump operation is much too stiff and results in too delayed an action when the throttle is quickly opened and pops back through weakness. The small brass cup and washer which house the felt washer are much too close and fit on the accelerator pump spindle and foul the latter on operation. It would appear better in this respect to locate the brass cup in the floatchamber cover and leave a reasonable clearance around the pump spindle with only the felt washer as a close fit. The spring also seems too strong for a job of this description. We cannot understand why the accelerator pump spindle is stepped up in diameter which means that the felt and cork washers cannot be readily removed in the case of renewal. | ||