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).
Performance and selection of spark plugs for various car models.
| Identifier | ExFiles\Box 162\6\ img143 | |
| Date | 25th April 1932 | |
| R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey} c. to SG.{Arthur F. Sidgreaves - MD} c. to Wor.{Arthur Wormald - General Works Manager} c. to E.{Mr Elliott - Chief Engineer} c. to Da.{Bernard Day - Chassis Design} c. to Hy.{Tom Haldenby - Plant Engineer} X4425 X1918. Hs{Lord Ernest Hives - Chair}/Lid.{A. J. Lidsey}11/MA. 25.4.32. SPARKING PLUGS, CARS. Our present standard plugs for cars are :- P.II Lodge 'C.3' Type (Mica and Porcelain). 20/25 HP. K.L.G. K.I. Type. (Mica Insulation.) The Lodge 'C.3' plug replaced the previous 'C' type which was an all porcelain insulated three point plug because it is better at high speeds. The 'C' type plug preignites badly after about three minutes full throttle running at high speeds; the C.3 Type plug is free from this trouble but has the disadvantage that it misfires badly on magneto ignition on pick up at speeds up to 30 m.p.h. in the P.II engine. When both ignitions are used, or on battery ignition only this fault cannot be detected. Recent tests also show that the K.L.G. 'K.1' plug misfires equally as badly on magneto ignition on P.II, as the Lodge 'C.3' plug. We have communicated with the plug manufacturers and are constantly trying out new type plugs in order to improve our standard. 20.G.IV was tried out for this reason with Lodge type S.1 plugs, these however have proved unreliable, both on this car and on other Exptl. cars. When a 20.G.IV returns we propose to test out on it a set of Lodge 'C' Type plugs, which are good on P.II for misfires at low speeds, we rather doubt however whether they will be sufficiently good at high speeds; we expect them to preignite. The present standard K.L.G. 'K.1' plug is very good for high speed work, but in view of the recent tests on P.II it may be found that it is a contributory cause of the prevalent low speed misfires on the 20/25 HP car, this point will be investigated. Hs{Lord Ernest Hives - Chair}/A.J.Lidsey. | ||