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).
Diagram and analysis of carburettor fuel mixture behaviour under acceleration and engine tilt.
| Identifier | ExFiles\Box 122\3\ scan0245 | |
| Date | 27th January 1941 | |
| Bm/TAS.{T. Allan Swinden}3/ET.27.1.41. - 2 - 2. The cone of mixture leaving the discharge tube will now descend at 5 1/2° out of vertical. Together with 1 1/2° backward tilt on the engine, this means that the fuel is descending at 7° towards the rear of the car-burettor. These offsets are shown in the sketch below. NORMAL FUEL LEVEL FUEL LEVEL INCLINATION - 5 1/2° DUE TO 3 FT/SEC² ACCEL. 1 1/2° DUE TO ENGINE MOUNTING DIRECTION OF TRAVEL THROTTLE SPINDLE PARALLEL TO C'SHAFT 3. The accelerator pump, which operates only during the first half of the throttle opening, i.e. that part of the range under considera-tion, shoots petrol towards the rear of the carburettor. 4. On the wraith type induction pipe the long straight branches are about 6" long and each feeds one cylinder. The gas speed at 13 M.P.H. is less than 12 ft/sec. and, since the inertia of fuel is nearly 60 times that of air, there is a ten-dency to strengthen the rear cylinder and weaken the front one. This effect is not great, but we have calculated that it would make 1/4% or a quarter of a ratio difference between front and rear. ----------- | ||