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 adjustments, focusing on quick thread adjustment, suction piston performance, and float material.
| Identifier | ExFiles\Box 13\3\ 03-page433 | |
| Date | 20th June 1932 | |
| -4- Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}2/MS.20.6.32.Contd. We have fitted a quick thread adjustment for the main jet to V.1353/6 which gives a movement of .050 on the jet, when the control is moved from rich to weak (approx 90°). With the original adjustment a movement of .020 was obtained. The quick thread is much more satisfactory when setting the carburetter. Running at full throttle, the suction piston is just seated at 550 RPM and using the quick thread adjustment the weakening of petrol consumption from full strong is 31.5% at this speed when using the full range of the mixture control. At full throttle 3000 RPM this range is reduced to 2% to 3%. With the original adjustment and under above conditions the weakness range from full strong is 12.5% at 550 RPM and 1% to 2% at 3000 RPM. SUCTION PISTON. The suction piston and chamber are to (Lec.3029) operating satisfactory with an all round clearance of .0015 to .0020. Our only trouble has been sticking due to the needle in its guide, but if these are lightly lapped in during the course of erection the movement of the piston is ideal. We are still waiting to try a larger diameter of piston for lower induction pipe depression and increased power at the high speeds. Floats made of 22 SWG material give us an ample working clearance between the float and its cover when setting the petrol level and are a much sturdier job than the 23 S.W.G. floats hitherto used. Hs{Lord Ernest Hives - Chair}/L.Swindall. | ||