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).
Carburetter starting and slow running issues, including proposed solutions.
| Identifier | ExFiles\Box 13\3\ 03-page431 | |
| Date | 20th June 1932 | |
| -2- Hs{Lord Ernest Hives - Chair}/Swdl.{Len H. Swindell}2/4A.20.6.32.Contd. (a) Direct feed passage from main jet into the diffuser without any unnecessary capacity between the two. (b) Slow running feed on same level from the diffuser and direct passage, but approx. .138 dia and not about .213 as shewn. STARTING. We have had considerable trouble in starting up from a dry carburetter, when using a petrol pump and starter motor. This trouble we have traced to air locking around the passages to the main jet. When the petrol has assumed its normal level in the float-chamber, the level in the diffuser is 1/8 to 1.00 lower, thus the feed to the slow running is still uncovered. As shown in Lec.302 petrol has to force air up and down, the latter being the possible cause of locking. Scheme to Lec.3123 is now being made whereby the petrol is fed upwards in a direct manner to the main jet. As a temporary measure to overcome this trouble we have drilled from the base of the diffuser in the carburetter casting to the slow running passage. SLOW RUNNING. The slow running of the carburetter could not be improved upon, the adjustment however could be simplified. We find that the slow running venturi (E.82876) is always adjusted to the same relative position in its body (E.82875) for correct idling mixture strength, so that these two could be made in one piece as (Y.1390). | ||