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).
Investigation into the cause and remedy for a whistling carburetter on a Goshawk-11 engine.
| Identifier | ExFiles\Box 5\4\ 04-page090 | |
| Date | 5th February 1923 | |
| X4228 CARBURETTER WHISTLING ON GOSHAWK-11. The most noticeable whistle is at approximately 1/6 open throttle, increasing with engine speed. There is also a very slight whistling at very low engine speeds, i.e. throttle only just opening. The whistling is not caused by sharp edges or burrs in the carburetter body. Carburetter was dismantled and every sharp edge and burr taken off, with no improvement. Carburetter whistles with air valve out, both jets and needles out and finally with everything dismantled but the carburetter body itself. (This was done by placing the car (6-G-11) on the bumper drums (after removing cams from same) and running the engine from the drums.) This apparently indicated that it was the throttle itself that was causing the noise, although there was nothing apparent to the eye to cause it. A comparison was then made between the Goshawk-11 butterfly throttle, an old small type 40/50 H.P. throttle and a Claudel barrel throttle; there is nothing to choose between the butterfly and piston type throttle, but Claudel throttle appears slightly quieter than the others. It was then noticed that the same Goshawk-11 carburetter when placed on different engines whistled more, or less respectively. It was then found that the cause of whistling was the annulus in the cylinder block, made between the end of the spigot on the throttle body and the recess in the cylinder block. When this space is filled in, leaving a smooth unbroken passage, whistling ceases. contd:- | ||