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).
Carburettor and ignition system adjustments for improved slow running and preventing engine backfiring.
| Identifier | Morton\M11\ img136 | |
| Date | 30th April 1921 guessed | |
| TO EFC. from R.{Sir Henry Royce} -2- R4/G1219 Contd. the spiral jet which has been fitted into this carburettor, does not give such good slow running as the usual plain taper one. If Mr. Hives thinks it is this latter, will he please send me a standard low speed spindle that I may try it myself. (Lately finished) I have re-read your December memo on this subject, and though I agree with much it contains, and thank you for your careful observation, especially re compact condensers, I want to correct two shortcomings. The make ratio would never do of very short duration using a heavy current and very low inductance, though the average current will be no more, there would be many disadvantages, so that I want you to work the coil and resistance etc. for the car work suitable for 3000 crankshaft revs. 1500 x 6 = 9000 ignitions per minute.With the standard volts and standard distance between the plugs in the maximum compression pressure we are likely to get at that speed (even in the new engines) with a make and break ratio of one to one, i.e. make duration of 1/18000 minutes, we hope then to be able to get extra good slow running, when we do not desire this ignition to work so quickly, by adjusting the battery ignition plug points at a greater distance than the standard(1/2 m/m or .020") I think Mr. Platford found .030" better for slow running. The other important point I want to correct is that I think you have missed my scheme of preventing the engine firing backwards if one fails to pull it over a compression, and it rebounds backways, as is so often the case. (Contd.) W H 5327 (200 L) (2'D '40B' SO-+-1A) 'B'w' S122[??]T | ||