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 effects of fitting a smaller low-speed choke tube to a carburetter to correct spitting.
| Identifier | ExFiles\Box 6\7\ 07-page104 | |
| Date | 20th November 1930 | |
| -2- by using a low speed choke tube .100" smaller on all its internal dimensions. This was fitted on a car which was bad for spitting in the silencer even after all the known palliatives had been applied. The effect of this was to make a marked improvement; whereas previously violent spitting occurred at all positions of the mixture control lever, After fitting the small choke it was possible to control the spitting by using the mixture control; at full weak, spitting was rather violent; at normal mixture, much less pronounced and at full strong only very occasional (much less violent) spitting took place. The effect on the general carburation was a marked improvement; the engine ran considerably slower than before (down to 140 R.P.M.) and smoother, and the mixture metering from the dead slow position right up to the speed at which the governor control will run the engine when at top of the quadrant was better than standard, the engine falling off weak or strong from the normal position at all speeds. A characteristic of the standard carburetter is that the mixture lever has to be moved over to strong to obtain good running at very low speeds; if the mixture is set to give this best low speed running in the normal position of the lever, then at higher speeds (say 400 R.P.M.) the mixture is very strong. The smaller choke appears to correct this entirely. we have only one at present running on 22-EX, and | ||