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).
Starting issues, petrol vaporization, and cooling system problems on test vehicle 22-G-V.
| Identifier | ExFiles\Box 101\1\ scan0161 | |
| Date | 17th March 1936 | |
| To Sg.{Arthur F. Sidgreaves - MD} from Rm.{William Robotham - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}12/KW.17.3.36. 22-G-V.{VIENNA} 15,000 Miles Test. Replying to Sg.{Arthur F. Sidgreaves - MD}2/E.17.3.36. The starting trouble on this car is exactly the same as the trouble we had with the Ph.III on the Stelvio in September last year, when we first discovered what it was. Briefly, the petrol vaporises in the float chamber due to the under-bonnet temperature, and so forces vapour out of the jet into the air silencer. After a few minutes the air silencer gets full of very rich mixture. When an attempt is made to start the car the first charge drawn in consists of this mixture which is too rich to fire. The trouble is worse on Hancock's car than on your car because in your case the petrol vapour can escape through two small vent holes drilled in the top of the float chamber, and on Hancock's car a special drain pipe has been fitted to carry petrol away should the carburetter flood, and this obstructs the passage of the vapour, making starting difficult. Removing the air silencer of course merely removes the place where the petrol vapour collects. There are several ways of dealing with the trouble, as we have been over all the ground on the Ph.III. It is merely a question of how to apply a cure with the minimum of disturbance to production. We cannot understand the water loss on 22-G-V as we do not have the trouble on an exactly similar car here. It is possibly due to a badly seating radiator cap. We shall know this almost immediately. The high water temperature was due to a modification fitted to the thermostat. Now that this has been removed the car will be no worse than yours. Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} | ||