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).
Letter to Zenith Carburettor Co. Ltd. about choke sticking issues on a 30 HP D.C. 42 carburettor.
| Identifier | ExFiles\Box 122\2\ scan0336 | |
| Date | 1st April 1938 | |
| 1033 Rm{William Robotham - Chief Engineer}/GR.{George Ratcliffe}14/JH. 1st April, 1938. The Zenith Carburettor Co.Ltd., Honeypot Lane, Stanmore, MIDDLESEX. For the attention of Mr. A.E. Palmer. Dear Sirs, 30 H.P. D.C. 42 Carburettor. We are still receiving complaints of choke sticking on the above carburettor and that the stronger spring E.61387 is not satisfactory. This is due mainly to the auxiliary valve spring being too strong, causing a flood of fuel to be drawn into the engine when starting cold. Further attempts to cure this trouble show that a reduction in the bearing area of the choke spindle is indicated and to revert back to your original P.17068 spring. The writer would like to know if you have any objections to the following details which are of course only experimental. (1) Choke spindle bearings are normally .253 dia. bore. They are then counterbored .265 dia. at one side .300" long and at the other side .200" long. This leaves a minimum bearing contact of .150" either side at .253" dia. These bearings appear to warp in any direction due no doubt to the lead/Zinc alloy used in die casting. (2) Choke spring P.17068. | ||