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).
Carburettor design, float chamber position, insulating washers, and performance characteristics.
| Identifier | ExFiles\Box 121\2\ scan0167 | |
| Date | 1st November 1934 guessed | |
| - sheet 2 - fitting a 1/4" union into it, and taking away from it a 1/16" diameter pipe to a point well below the bottom half crankcase joint. This drain is always open to the atmosphere and owing to the long length of small diameter pipe used, there is actually no appreciable leak into the induction system and it does not therefore affect the carburation. We raised the question of the position of the float chamber relative to the jets, and told Mr Mills that our practice was always to place the float chamber forward of the jets. Mr Mills said that owing to the facts that the float chamber of their carburetters was arranged in quite close proximity of the jet and owing to the very small amount of petrol carried in the float chamber, they did not find that the centrifugal effect consequent upon fast cornering affected the carburation in any way. He stated that in the event of our tests Showing that their carburetters were suitable to us for production, they would be perfectly willing to produce special carburetters for us having the float chambers in any position we desire. Mr Mills suggested that when we get the downdraught carburetters fitted to the Bentley engine it might be helpful to us if they sent their Mr Peach along to give us any assistance and advice that he could. We told him that we should probably be grateful for his assistance and would let him know at a later date if we required his services. We asked Mr Mills the exact purpose of the insulating washer which in many cases is fitted between the carburetter and the induction pipe manifold flanges when downdraught carburetters are employed. He stated that this feature was essential with downdraught carburetters especially where extensive exhaust heating was employed. The object of the washer is to prevent the boiling of petrol in the float-chamber which would otherwise occur due to the heat conduction from the heated manifold to the carburetter. Wraith. We asked Mr Mills his opinion as to whether dual downdraught or dual updraught carburetters would be preferable on this type of engine. He preferred downdraught carburetters on the score of better acceleration and slightly increased maximum power. Owing to the provision of a good | ||