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).
Report comparing the road test performance of Twin Zenith and Solex carburetters on different engines.
| Identifier | ExFiles\Box 5\4\ 04-page244 | |
| Date | 11th June 1930 | |
| To H.{Arthur M. Hanbury - Head Complaints} From HA/ACL. c. to Ed.{J. L. Edwards} Mor. c. to L. DA.{Bernard Day - Chassis Design} c. to RY. TWIN CHOKE CAR CARBURETTERS. We have carried out a few road tests on the Twin Zenith carburetter on a 'Japan' engine but although we have not yet got the mixture quite right for road conditions we have been able to get a very good general impression of its performance compared with the Solex carburetter we tested on the Phantom. The metering of the Zenith is obtained by multi jets and not of the simple emulsion type diffuser as used in the Solex. The single jet of the Solex would appear to offer certain advantages because a jet type mixture control could be incorporated. One marked difference between the Zenith and Solex is in the snap opening from low speeds on top gear. The Zenith depends upon its pump for this at anything below 10 M.P.H. while the Solex gives good results without a pump to quite low speeds. The Solex, however, had much smaller choke areas for the size of the engine in comparison with the Zenith on 'Japan'. The free choke area of the Solex on Phantom was .893 sq.in., while we used the equivalent of .67 sq.ins. for the Zenith on 'Japan'. We should suggest that for a Rolls-Royce design of twin choke carburetter we should start off with a larger | ||