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).
Technical note discussing engine priming, induction pipe capacity and hand pump operation for starting.
Identifier | ExFiles\Box 31\3\ Scan019 | |
Date | 13th January 1915 guessed | |
Wor{Arthur Wormald - General Works Manager}/EH10/L13115. Sheet 2. a very fine spray and with that the engine starts up consistently on the third compression, this is 100% efficiency. From my tests I have found that if I use a fine spray it is necessary to give considerably more strokes on to the hand pump. The whole point is that the capacity of the induction pipe is the limit to the amount of mixture that can be stored up, the capacity of the pipe is only sufficient to charge one or two cylinders, the engine then has to rely on the petrol which is laying in the pipe, so as long as the petrol which is supplied by the primer wets the whole of the inside of the pipe so as to take full advantage of the surface for vapourization that is the most it can do. This is confirmed on the engine, if we use a fine spray and give say 8 strokes of the pump the engine fires on the third compression but only gives one puff, it does not start, it will take say from 40 to 50 strokes before enough petrol is in the pipe to start the engine and keep it running. I can get just as good results by having not such a fine spray and less strokes of the hand pump. The priming arrangement performs two operations (1) It stores up xxx in the pipe a mixture which will ensure the engine to start on the third compression. (2) It provides petrol distributed about inside the pipe which will keep the engine running until the carburetter picks up. | ||