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).
Phantom III carburetter consumption tests following alterations to main jets and choke spring.
| Identifier | ExFiles\Box 93\2\ scan0213 | |
| Date | 16th November 1937 | |
| 308 if any changes file in 124a. Rm{William Robotham - Chief Engineer}/GR.{George Ratcliffe}6/MH.{M. Huckerby}16.11.37. PHANTOM III CARBURETTER - SECTION 5080. REPORT ON CONSUMPTION TESTS. The following alterations were found to give improvement in consumption. Main metering jets .056 instead of .058. These smaller jets required a stronger choke torsion spring to give a reasonable control of mixture, when driving the car away with the engine cold. Spring E.87987 was shortened .450" and proved satisfactory. A memo and sketch has been sent to By.{R.W. Bailey - Chief Engineer} with a request for alterations to detail, so that the standardisation sheet may be issued. Tests were carried out on production chassis in conjunction with Mr. Archer with satisfactory results. All consumption tests were carried out with the four port cylinder heads and manifolds, as no standard unit was available. PETROL CONSUMPTION TESTS. Main Jets. Distance. Average Speed. Consumption M.P.G. 35-EX. 37-EX. standard .058 72 miles 45 M.P.H. 11.0 11.0 .056 72 " 45 " 11.8 11.2 standard .058 84 " 44 at 45 M.P.H. } 9.3 9.1 40 " 60 " } .056 84 " 44 " 45 " } 10.0 9.5 40 " 60 " } standard .058 84 " 44 " 45 " TOP GEAR 9.6 40 " 55 " OVERDRIVE 11.0 .056 84 " 44 " 45 " 10.2 TOP GEAR 40 " 55 " 12.2 OVERDRIVE | ||