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).
List of alterations to the governor and relay piston for a 10,000-mile test on the 12-EX, with a corresponding ignition advance curve graph.
| Identifier | ExFiles\Box 65\1\ scan0196 | |
| Date | 23th April 1926 guessed | |
| contd :- -4- have fitted up on 12-EX for the next 10,000 miles test has the following alterations. (1) Aluminium governor weights. Half the mass of the original steel weights. (2) Duralumin small inner relay piston. (3) Improved arrangement of leather and ring, large relay piston. (4) 7° initial advance on relay obtained by dropping floor of chamber .100". (Neck of governor rod already as close as possible to small piston). (5) Return spring over relay 12 lbs. in retard position as at present. (6) Present standard magneto with sleeve friction 2 1/4 lbs. and light return spring. The resulting advance curve with oil pressure of 10 - 15 lbs/sq.in. at 60°C is shewn in Graph 11. Diagram Text: Floor dropped .100" Graph 11 Text: Y-Axis: IGNITION ADVANCE X-Axis: ENGINE R.P.M. Curve 1 (dashed): LAG WITH ALUM GOV WTS AND DURALUMIN SMALL RELAY PISTON Curve 2 (solid): INITIAL ADVANCE 7° to 8° Annotation: { LIMIT OF ADVANCE FOR MAX POWER } | ||