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).
On tests of a new ignition oil relay with metal piston rings, including proposed ignition advance curves for Phantom and other engines.
| Identifier | WestWitteringFiles\Q\December1926-January1927\ 35 | |
| Date | 9th December 1926 | |
| To R.{Sir Henry Royce} From Hs{Lord Ernest Hives - Chair}/Rn.{Mr Robinson} c. to BJ. Nor.✓ c. to E.{Mr Elliott - Chief Engineer} DA.{Bernard Day - Chassis Design} c. to EY. ORIGINAL. Hs{Lord Ernest Hives - Chair}/RnL/LG9.12.26. X8685\n̶x̶7̶6̶8̶5̶ IGNITION OIL RELAY. We have now completed a number of tests on the new relay with metal piston rings and longer travel to LeC.2242. This has run 10,000 miles on 12-EX without loss of efficiency or failure, so that we believe the metal piston rings will prove reliable in service and reasonably immune from sticking due to impurities in the oil. We attach two curves of ignition advance obtained with the modified form of springing. One we have arranged on 7-EX (A.{Mr Adams}) This curve is similar to that on 12-EX only the ignition is not timed quite so late. It was found that the 13° B.T.C. timing on 12-EX affected the low speed performance and the timing was altered to 17° B.T.C. We think that curve A.{Mr Adams} gives the best all round results for use on the present standard Phantom engine, reducing detonation with the minimum loss of power. We think curve B. could be used on 10-EX and engines where increased efficiency is desired at the higher speeds. However, an aluminium head will probably be adopted on such engines, when the characteristics of the ignition advance curve required will be altered. We suggest the following slight alterations which we have tested out and found satisfactory :- contd :- | ||