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).
Carburettor freezing, fuel distribution issues, and potential solutions for cold starting problems.
| Identifier | ExFiles\Box 123\1\ scan0036 | |
| Date | 21th February 1940 | |
| -4- With regard to type (a) of freezing up in the rich position before starting, the only method of reducing the chances of this is to reduce as far as possible the contact surface between the needle and the bridge piece through which it passes. This is where freezing is most likely to occur, hence counterboring may be advantageous. This can equally well be applied to anti-freeze measures I or II. After a considerable number of tests had been carried out by Ratcliffe it was determined that the best method of overcoming the problem of bad distribution was by carrying the starting fuel along gallery pipes cast in the induction pipe and feeding it to the engine vertically downwards opposite each main carburetter entry. This has been carried out on induction pipe XB.4995. It does not provide a consistent cure, nor is this possible, due to the variable air leak past each S.U. carburetter piston. This is a trouble with this Starter which we alone have to face, owing to the spring dampers which we fit to prevent the piston from rattling on the bridge when the engine is idling. In this they are efficient, but they provide an air leak which is variable, and prevent that sealing of the induction system which is so essential to an immediate cold start. Rm{William Robotham - Chief Engineer}/TAS.{T. Allan Swinden} | ||