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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).
Carburetter throttle synchronisation for slow running adjustment on the 4 1/4 Litre Bentley.

Identifier  ExFiles\Box 131\3\  scan0041
Date  4th March 1939
  
1113 . also . 208

To GWH.{George W. Hancock - Head Chateauroux} from Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}

Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}5/MH.{M. Huckerby}4.3.39.

4 1/4 LITRE BENTLEY.

SLOW RUNNING ADJUSTMENT.

On the new B.V. we wish to make use of past experience to incorporate the best possible method of maintaining synchronisation of carburetter throttles.

Our present knowledge is as follows:-

(a) We say that the best way of initially synchronising the throttles is to do it with the engine stopped. The throttle stop is released so that the throttles can shut completely.

The locking device between the throttles is released so that both throttles can be shut. The coupling is then locked up again, and the throttle stop is used to determine the actual tick-over speed. There is only one throttle stop on the rear carburetter; the return spring being situated on the front carburetter. In this way the couplings between the two throttles are "wound up", so that any slack is thus taken care of.

This method of adjusting the carburetters is as laid down in the instruction book.

We wish to know whether there would be anything to be gained from fitting a throttle stop to each carburetter, and/or a return spring on each carburetter.

What is your experience in service ?

Rm{William Robotham - Chief Engineer}/CTS.{C. Trot Salt - Carburation}
  
  


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