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).
Thermostat and carburation issues, comparing water-heated and exhaust-heated throttles on the Phantom II.
| Identifier | ExFiles\Box 39\4\ Scan193 | |
| Date | 12th November 1930 | |
| X3499 Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} A.{Mr Adams} Wormaley G.{Mr Griffiths - Chief Accountant / Mr Gnapp} Symes. O.{Mr Oldham} F.{Mr Friese} R.{Sir Henry Royce} EP{G. Eric Platford - Chief Quality Engineer}1/H12.11.30. re. THERMOSTAT - CARBURATION. With reference to R1/M27.10.30., a copy having been sent to me, I take it that some expression of our experience is required. In the first place, we were not satisfied with the carburation of the early Phantom II cars fitted with the water heated throttle. A water temperature of 80° had to be maintained to make adjustments which gave reasonably reliable and consistent results. We suffered to some extent from "loading up", spitting in exhaust and fumes when "luffing up", features which were very much aggravated when running at lower temperatures. Acceleration was also poor at these lower temperatures, and to overcome this there was the general tendency to strengthen up the jets with the ill effect above mentioned. The exhaust heated throttle improved matters considerably. We can now make our adjustments practically mechanically and obtain consistent and reliable results, if not there is a cause which can be cured. Good carburation is maintained with water temperature from 70°C upwards (as per Instruction Book). We can definitely weaken off the mixture under any condition of running by means of the control. Economy and power can be obtained as desired. We do not suffer from "loading up", maximum performance and acceleration are also obtained. At lower temperatures, however, the mixture is somewhat attenuated. The carburation feels weak, but we must not strengthen up especially the low speed jet otherwise we suffer from the tendency to "load up", also from the fumes and spitting in the exhaust, as already mentioned. The latter features we are not entirely free from even at the best. From the short run I had with 25-EX (just prior to Hs.{Lord Ernest Hives - Chair} taking straight to U.S.A.) carburation suffered from the above and did not compare favourably with our CONTD:- | ||