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).
The testing methods for Vauxhall 10 HP and 14 HP carburetters, including the use of a flow bench.
| Identifier | ExFiles\Box 122\4\ scan0173 | |
| Date | 30th June 1938 | |
| -3- Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}8/JH.30.6.38. All the Vauxhall 10 H.P. and some of the 14 H.P. carburetters are tested in this way, a 3% error on either side of the master carburetter curves being allowed. Whereas this type of rig is adequate for checking a large quantity of carburetters in production, it is not sufficiently accurate for original work or modification. Carburetters which are found doubtful on this rig are again checked on the complete rig before rejection. The complete experimental department Flow Bench is used for original development, modification to existing types, and the supplying of master carburetters to the production rig, the setting for this carburetter first having been obtained on test bed and the road. PART THROTTLE CURVES. FULL THROTTLE CURVES. FIXED THROTTLE CROSS SECTIONS. FIXED AIR CROSS SECTIONS. It may be used for obtaining the well known part throttle and full throttle curves, and in addition may be used for fixed throttle and fixed air cross section. With the former, the throttle is set at a given air flow, the air flow then being reduced by integral amounts and the corresponding fuel flows noted. The resulting mixture ratio/air flow curve represents the mixture ratio characteristics when accelerating up to the given air flow. By allowing more air to flow an over run characteristic may be obtained. With the fixed air cross section the throttle is again opened to a given air flow. The air vacuum valve from the blower is then slowly closed, the throttle opened to maintain air flow, and integral readings of fuel flow and carburetter depression taken. An over run characteristic may be obtained by opening the vacuum valve. From the figures obtained it is possible to deduce curves of mixture ratio against carburetter depression for the given air flow. Hence a picture is obtained of the operation of the carburetter throughout the range of depression, independent of air flow. | ||