Report comparing normal-reach and long-reach spark plugs and their effect on fuel economy (M.P.G.).
| Identifier | ExFiles\Box 127\4\ scan0189 | |
| Date | 8th March 1940 | |
| - 2 - Cont'd. {John DeLooze - Company Secretary} Rm {William Robotham - Chief Engineer} /CTS. {C. Trot Salt - Carburation} 5/ML.8.3.40. These protruded into the combustion chamber by 3/8" and the improvements claimed are over and above their already "established" claims of improvements resulting from wide plug gaps. We have had a chance however, during this last visit, of reviewing actual figures obtained by the testers interviewed. These were "log-book" figures. NORMAL-REACH PLUG. LONG-REACH PLUG. M.P.H. GAP. GAP. GAP. GAP. .020. .040. .020. .040. 20 66.0 68.5 70.4 30 58.6 58.7 59.0 59.6 40 47.3 48.4 49.3 49.8 The above figures represent M.P.G. at constant speeds, using the Zenith mileage tester, on a 10 n.p. Vauxhall car. Two types of plug were used; the normal A.C. short reach plug, similar to the shortest reach plug that we have used, and the special A.C. long reach ; type S.P.211. We have a sample model of the latter. Apart from the fuel economy figures, it was stated that the longer reach plug improved the general running of the engine for smoothness. etc., After examining the combustion chamber this is really not very surprising as the plug position is badly pocketed by one of the patent saucer-shaped recesses. - Continued - | ||
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).