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 improvements regarding sticking choke spindles on Stromberg carburettors.
| Identifier | ExFiles\Box 123\1\ scan0032 | |
| Date | 19th February 1940 | |
| 1036. To FD.{Frank Dodd - Bodies} c. Rm{William Robotham - Chief Engineer}/WYM.{G. Harold Whyman - Experimental Manager} c. Rm{William Robotham - Chief Engineer}/CRS. Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden}5/ML.19.2.40. Choke Spindles on the Dual Stromberg Carburettors. On the Wraith type DC 42 Stromberg carburettor trouble due to sticking choke butterflies was largely overcome by counterboring the spindle bearings so reducing the bearing area by about 2/3. In this case the brass spindle was carried directly in the alloy die casting, and this not only created a bad bearing but was liable to distort when the air silencer borer was clamped down. The Dual Stromberg carburettor avoids the trouble in two ways:- (a) the brass spindle is carried in bearing bushes which our Lab. tells us are of stainless steel. (b) the die casting has been so reinforced as to cause distortion due to the air silencer clip a virtual impossibility. Even the choke butterflies on our oldest carburettors are remarkably free and show no signs of the stickiness associated with their opposite numbers on the Wraith type carburettor. The only carburettor not fitted with stainless steel bushes is on 4.B.50. Although the choke butterfly appeared to be very free the bearings were counterbored on this carburetter in order to raise it above suspicion. Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} | ||