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).
Standardisation of spark plug sizes, advocating for the 14mm thread.
| Identifier | WestWitteringFiles\W\September1931-November1931\ Scan054 | |
| Date | 23th October 1931 | |
| ORIGINAL To R.{Sir Henry Royce} From Hs.{Lord Ernest Hives - Chair} c. to Sg.{Arthur F. Sidgreaves - MD} Mor. c. to Rg.{Mr Rowledge} E.{Mr Elliott - Chief Engineer} c. to Ry. Da.{Bernard Day - Chassis Design} SPARKING PLUGS. Hs.{Lord Ernest Hives - Chair}5/MJ.23.10.31. X4425, X1918, X5970, X7970. It appears to be becoming definitely established that the smaller size of sparking plug is likely to be standardized. The sparking plug people say that they can make a plug with a 14 mm. thread equal to the present standard plug with 18 mm. thread. There are, of course, plugs made with 12 mm. but in their opinion this is on the small side for a general purpose detachable plug. We understand that the 'Nash' car people and the Chrysler', are making some of their models fitted with 14 mm. plugs. Most of the motor-cycle people have standardised a 14 mm. plug. It should therefore only be a question of a short time before supplies of these plugs are available in all countries. We are sending to R.{Sir Henry Royce} samples of plugs. Hs.{Lord Ernest Hives - Chair} | ||