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).
Performance and potential improvements for an 'SS' carburetter.
| Identifier | WestWitteringFiles\T\2July1928-December1928\ Scan199 | |
| Date | 10th November 1928 | |
| HS.{Lord Ernest Hives - Chair} FROM R.{Sir Henry Royce} C. to BJ. WOR.{Arthur Wormald - General Works Manager} BY.{R.W. Bailey - Chief Engineer} SG.{Arthur F. Sidgreaves - MD} ORIGINAL R2/M10.11.28. 'SS{S. Smith}' CARBURETTER. X1080 I am very pleased with the first run on the RR. single expanding carburetter: quite as good as one could expect. I have no intention of hurrying this for the 1st. SS.{S. Smith} It will require too long to prove its reliability. Also the results with present standard pattern are so good that there is no real hurry. We should however keep it going when nothing else presses. Apparently the parts move as we intended, but the restrictor does not come sufficiently out of the throat. (1) Perhaps we could get better advantage by making the throat larger in dia., the restrictor acting as the venturi. (2) At first it would seem that we ought to increase the stroke of the restrictor because if it would only come out of the way the throat would be large enough. (3) Can we get some advantage by lowering the restrictor say 1/10th"? Can we do a little of each - (1) (2) & (3) - and so make a fair amount of difference? There does not seem much wrong with the spring over the actuating piston because the restrictor moves to its final position at about 1¼" hg. It might be altered to 2" by a stiffer spring until you get it to act well under such conditions. Supposing this occurred at 2000 revs. then above this speed it would follow RR.CH. up to just over 3" at 3000., and BHP. of 125. Apparently you think there is too much emulsion air, because you cannot get enough petrol. I should have thought the holes in venturi are too small or too few, or holes or passage earlier than the jet too free, SO preventing the engine suction getting to the jet - i.e. what is the suction in the jet compared with the throat suction? Don't let me put you off your own train of thoughts and line of experimentaing: the above are suggestions. I am surprised you are only asking for the area to be increased from 1.2, which I understand the carburetter gave, to 1.53, which gives over 130 BHP. - i.e. 25% - but perhaps you are right. You got maximum 108 instead of 132 - 108 X 125/100 = 135. R.{Sir Henry Royce} | ||