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).
The Goshawk-11 carburetter development and road testing at Le Canadel.
| Identifier | ExFiles\Box 46\2\ Scan135 | |
| Date | 8th April 1922 | |
| y4086 To EP.{G. Eric Platford - Chief Quality Engineer} from R/Hs.{Lord Ernest Hives - Chair} c. to Hy.{Tom Haldenby - Plant Engineer} c. to Da.{Bernard Day - Chassis Design} c. to E.{Mr Elliott - Chief Engineer} c. to Wor.{Arthur Wormald - General Works Manager} c. to CJ. and BJ. c. to PN.{Mr Northey} c. to C. c. to Rs.{Sir Henry Royce's Secretary} (for file). R/Hs{Lord Ernest Hives - Chair}/LG8.4.22. 4-GOSHAWK-11 - Le CanadelHenry Royce's French residence. X4219 X4086 This is running extremely well here - about 2000 miles since leaving London. With the very silent exhaust and carburetter which is extremely good for all low speeds, the car seems to do a real 60 M.P.H. (mean with and against ordinary wind) on level with every-thing on, including the very effective splashers. Carburation. We have worked further with the carburetter and have come to the conclusion that for perfect picking up and with the present setting of spring and ports in the extra air valve, our best high speed throat is .625 venturi bore. This contradicts our and other previous remarks, that the loss of power at low speeds was richness. We cannot get such an effect (over-richness) with any parts which we understand have ever been tried. Larger carburetter. I think it is possible that we may be able to run quite well with a larger throat later, if we increase the ports and the diameter of the lower part of the air valve & and in this way get a complete larger carburetter which should give us more power, if the carburetter proves to be the serious restriction, but one feels that we ought to get our extra power first by freer exhaust, then prove it is the carburetter before increasing the way through the carburetter. It will be remembered that the new high speed throat for production cars will be .625 bore and will be made of brass or bronze and not aluminium. Later test on Carburation. Our car is running excellently well. I was quite wrong in recommending a larger high speed throat, .625 is the best we have tried. There may be a possibility of using a larger air valve, we have asked for the lower part of this to be about 1/8 larger in diameter so far all our tests show the loss of power is through a weak spot (not strong as was understood some time ago). We have tested the S.U. Carburetter in all ways that are useful and although this is fairly good and simple, it is not quite so good as ours. (but unfortunately, much too good). We are more silent, more consistent at slow speed and so far we show the better economy being - 23 miles against the S.U. 21 per gallon. A very persistent air lock has occurred in the gravity part of the system, i.e., from the autovac tank to the float chamber. We can avoid this by having it all down-hill and not up-hill contd:- | ||