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).
Investigating a potential overheating issue in a car, possibly due to a stuck exhaust butterfly baffle.
| Identifier | ExFiles\Box 24\5\ Scan023 | |
| Date | 25th September 1924 | |
| R.R. 493A (50m) (D.B. 175 25-9-24) J.H.D. EXPERIMENTAL REPORT. -2- Expl. No. REF: Hs{Lord Ernest Hives - Chair}/Rnl/LG.4.25. We are certain that had there been any difference which could have been noticed by a customer that we should have been able to measure it. We can locate differences of 3% quite definitely, and confirm the results without difficulty. We are therefore forced to the conclusion that either something is definitely wrong with the car 67-AU or that the Depot in Australia are not aware of the fact that the present standard 40/50 HP. is likely to boil under the conditions which they mention. With regard to something being wrong with the car - we can think of only one thing that may have been overlooked. The exhaust butterfly baffle for supplying heat to the carburetter is capable of completely cutting off all six cylinders from the silencer with the single branch scheme, whereas with the double branch scheme only three cylinders could be thus affected. If this butterfly was to stick in the closed position, the key on one of the small levers operating it might shear, the accelerator therefore would function fairly satisfactorily, but serious overheating would occur at high speeds due to the enormous back pressure so caused. It is easily detected by the strangled exhaust note when running with the cut-out open. Unless some means of checking the pump delivery and circulation are available, detecting a restriction in the water circuit might be difficult. We should like to recapitulate the facts we have ascertained during the course of our road tests at the Works. | ||