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).
Page 2 of an experimental report detailing engine tuning and testing procedures.
| Identifier | ExFiles\Box 66a\1\ scan0039 | |
| Date | 28th January 1925 | |
| EXPERIMENTAL REPORT. -2- nut just seats again - from this point it should be advanced - still anti-clockwise - for approximately half a turn. The engine should be run light with the ignition about 3/4 advanced on the quadrant and the throttle opened until the air valve just starts to lift. It is better for the air valve to be just on the point of lifting but if there is any lift at all, it should not exceed about .025". The mix air valve can be marked by a fine pencil line along the bottom of the air ports when it is in its right down position so that the point of lifting can be readily detected. The speed of the engine when the air valve starts to lift is about 250 r.p.m. The mixture control can now be varied until the engine gives the best running and this can be detected if the cut-out is open, by the smooth 'spimming' running of the engine. The engine revs. will be greatest on this throttle setting when the mixture is correct. The jet should be so adjusted to give this running - which to obtain very accurately can be checked with a rev. counter - with the mixture control in its central position. The high speed jet must be set with the engine under full load and the spark advance set to give maximum torque. This should be set at an engine speed of 1500 r.p.m. full load so that it gives maximum torque for the minimum consumption with the mixture control in the central position. The torque should just start to fall off when the mixture control is advanced one notch weak from central position. The average consumption at this speed is .65 pts/HP/hr. with cut-out open. contd :- | ||