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 recommendation of various spark plug brands for different markets.
| Identifier | ExFiles\Box 50\2\ Scan041 | |
| Date | 2nd February 1921 | |
| To EY. from R.{Sir Henry Royce} c. to CJ. c. to HS.{Lord Ernest Hives - Chair} c. to MP. c. to Hm.{Capt. W. Hallam - Head Repairs} c. to Fn. c. to H.{Arthur M. Hanbury - Head Complaints} c. to R.R. of America Inc. (for the attention of OY) X.4295 X.1812 RE SPARKING PLUGS X.4295 X.4196 X.4313 X.2835 With reference to your BY11/F14.2.21, a few days ago I sent a memo recommending Champion Plugs as the standard for U.S.A. cars and Mercury standard for English built cars. I agree that cars for U.S.A. and Canada should be despatched without plugs, but dummies to keep out dirt, and certainly agree to ordering 500 Champion @ 5d. each in U.S.A. and 1,000 Mercury @ 1/2 each or less, at our works. I consider the Mercury the better from my observations, but this is subject to, and over-ruled by practical experience. Lodge mica porcelain ones such as I have used, should be discouraged at once as quite unsatisfactory. My little pump engine is excellent for testing the value of plugs from a sooting-up point of view, as the combustion chamber is divided into two; one part where the plug is, gets the over-rich mixture. This is further diluted with extra air (by valve) in part of the combustion chamber where the piston is. Thus, all cool working plugs are soon sooted up. Mercury, Champion and (Lodge with porcelain collar) all clean themselves. The old Bosch (four pointer) Lodge (mica) K.L.G.(mica) etc. fail in a few minutes hours quite consistently. Contd. | ||