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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).
Issues and proposed modifications for the 20/25 HP carburetter.

Identifier  ExFiles\Box 102\1\  scan0233
Date  27th December 1934
  
X5080

To E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}
c. to Wor.{Arthur Wormald - General Works Manager}
c. to By.{R.W. Bailey - Chief Engineer}
c. to Mx.{John H Maddocks - Chief Proving Officer}

Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}1/KW. 27.12.34.

20/25 HP. Carburetter.

We have appreciated since the introduction of this carburetter that there is a tendency for it to be inconsistent on the pick-up. This has possibly been a contributory cause to some of the complaints of poor pick-up which we have received. The two sources of trouble are :-

(1) The balancing arrangement of the carburetter. This was dealt with fully in the memo. Hs{Lord Ernest Hives - Chair}/CTS.{C. Trot Salt - Carburation}24/KW.8.10.34. and is a feature which has caused the Test Dept. quite a lot of trouble.

(2) With the throttle edge slow runner in its original position, the changeover position occurred between 10 and 20 m.p.h. and it was exceedingly difficult to get perfect carburetion during the changeover. By putting the throttle edge on the other side of the throttle it has been made to die away more quickly, and the changeover position now comes at 8 m.p.h.

We consider that these two modifications produce a very definite improvement in the existing semi-expanding 20/25 carburetter and we recommend that Design modifications should be got out to incorporate them. We then suggest that 6 carburetters are put through and submitted to the Test Dept. with a view to standardisation as soon as possible.

Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer}
  
  


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