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).
Engine starting, carburation, and idling issues for car 21-0-IV.
| Identifier | ExFiles\Box 5a\4\ 04-page242 | |
| Date | 29th January 1936 | |
| 21-0-IV. ENGINE. Starting. We found no difficulty in starting up from cold. The procedure, however, is that the throttle must be opened up after the engine has started to fire, and the choke control lever moved to approx. 1/4 open, otherwise the mixture becomes too strong. The control lever for the choke we found it necessary to leave 1/4 closed for a matter of 10 minutes, to ensure getting away. We had during the first day's run in traffic a distinct flat spot in the carburation when getting away from the signal lights. The engine would pick up, then cease for a moment, picking up again immediately. We suspected the acceleration piston, and removed it. The result was very poor acceleration but no definite miss. We also had trouble with the engine maintaining revs. after the throttle should have been closed. The removal of the accelerator pump cured this trouble. Two faults therefore originate from the sticking of the accelerator pump - (1) A misfire accelerating from stop. (2) Causes the throttle to remain open. Idling of the engine at traffic stops gave no trouble and no pulsations could be felt provided that the ignition lever was retarded five notches. A comparative test of idling with Sg{Arthur F. Sidgreaves - MD}'s 25 HP. car proved that 21-0-IV ran as evenly with the ignition retarded. Sg{Arthur F. Sidgreaves - MD}'s car was better with the ignition full advanced. The carburation of his car was slightly stronger idling than 21-0-IV. | ||