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).
Spark plug selection, balancing heat characteristics, and engine distribution improvements.
| Identifier | WestWitteringFiles\G\September1921\ Scan39 | |
| Date | 1st September 1921 | |
| To R.R. of America. from R.{Sir Henry Royce} -2- R16/G5/9/21 Contd. we have known it to occur badly, and have had to select the plugs accordingly. You will remember that it is just as important to have a plug in which the heating of the insulation is sufficiently high to prevent the deposit of carbon, so that we are between the two fires, of plugs which get too hot in working and those which keep too cool. Only road experience can find the right ones. These we must watch most carefully and not be tempted to lightly make a change. Personally, I have been using the Mercury plug made in Birmingham, England, using French porcelain and I have had no reason to wish for anything better. They are inexpensive. Mr.Hives has made good progress with better distribution very suitable for our present engine, by using the Doris scheme and our throttle exhaust heated. R.{Sir Henry Royce} | ||