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).
Design, adjustments, and operation of a starting carburetter for the 40/50 HP chassis.
| Identifier | ExFiles\Box 74\2\ scan0058 | |
| Date | 16th December 1921 | |
| To R.{Sir Henry Royce} from Hs.{Lord Ernest Hives - Chair} c. to CJ. c. to R.{Sir Henry Royce} c. to Da.{Bernard Day - Chassis Design} c. to BY.{R.W. Bailey - Chief Engineer} c. to EF. c. to Hs.{Lord Ernest Hives - Chair} c. to FN. c. to EWT. for R.{Sir Henry Royce} R.{Sir Henry Royce} Inc. Attention of OY. X4387 Hs{Lord Ernest Hives - Chair}1/LG16.12.21. RE. STARTING CARBURETTER FOR 40/50 H.P. CHASSIS. X.4390. X.4387 The starter carburetter which we sent to Springfield in August was developed during Summer conditions and did not embody some of the latest knowledge. We have never been able to understand however, why it was necessary for Springfield to use a weaker spring than the one fitted. We adjust the strength of the spring on the moving throat so that when the engine is being turned by the starter under any condition, the throat does not move, it is only when the engine fires that the throat opens up. We have also made it now so that when the throat is in the rest position, the annular passage round the jet is only .010". We have proved that for starting with a dead-cold engine we want all suction possible on the jet. Sufficient air leaks through the inlet valve guides or through the exhaust valve on the exhaust stoke. A positive quick start can always be obtained from the engine if, when the pilot jet is applied to an existing car, the primer connections are left intact, the primer can then be used in conjunction with the pilot jet. This ensures that the petrol is delivered right into the induction pipe and makes certain the first explosion after, that the pilot jet can easily carry on. We have not found this necessary under ordinary conditions; by ordinary conditions we mean, using 20% paraffin, but if the contd:- | ||