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).
Tests of various spark plugs for the 25/30 HP chassis.
| Identifier | ExFiles\Box 58\2\ Scan323 | |
| Date | 24th April 1936 | |
| TO HX. c. to LY. c. to DY.{F R Danby} c. to Wst. cc to Lmdk. cc to Gypgld v6000. HS{Lord Ernest Hives - Chair}/GR.{George Ratcliffe}6/JH. 24.4.36. 25/30 Sparking Plugs. The following figures are the result of tests carried out on 21-G-IV and GUL-20 production chassis with the object of deciding the correct plug for the 25/30 HP. All plug gaps were carefully set at .020". K.L.G. 850 even at 12 m.p.h. Lodge RL.14 " " 8 m.p.h. Lodge X.306 " " 8 m.p.h. K.L.G. 831.LR{Mr Ellor} " " 6 m.p.h. The plugs K.L.G. 850; K.L.G. 831.LR{Mr Ellor} and Lodge RL.14 were then examined in section. It was found that the best plug K.L.G. 831.LR{Mr Ellor}, for slow running, had the largest gas volume around the points. With this in view, K.L.G. 850, and Lodge RL.14 were altered to give greater volume round the points. K.L.G. 850 fitted with two additional internal washers i.e., raising central electrode in body .060" reset at .020". Lodge RL.14 fitted with one additional internal washer i.e. raising central electrode in body .030", reset at .020". K.L.G. 850 modified now even at 7 m.p.h. Lodge RL.14 modified now even at 6 m.p.h. All plugs with the exception of Lodge X306 were tested on both car and chassis with identical results. The objection to K.L.G. 831.LR{Mr Ellor} is due to the mica insulation being rolled on the central electrode. | ||