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).
The design and performance of engine and gearbox components including connecting rods, crankshaft, carburetter, and supercharger.
| Identifier | ExFiles\Box 128\1\ scan0178 | |
| Date | 12th November 1934 guessed | |
| -2- Connecting rods are plain H section, unnecessarily strong. Plain white metal big ends and bronze small end bushes are used. They put big ribs across the cap, because they think a weak cap can cause breaking up of the other half of the big end. The crankshaft is 3-bearing, with 2⅛" pins, and counterbalanced. They say there is a small period at about 2300 R.P.M., but no trace anywhere else. They run up to 8000 R.P.M. or above on the 1500 c.c. engine sometimes. The centre bearing is a Hyatt flexible one, not needle rollers. The Hyatt rollers are about an inch in diameter. They run on the soft shaft, which causes flats. All the oil to the big ends is fed through the two end journals, i.e. each end journal feeds three pins. There are no intermediate journals to interfere though. Oil ways appeared to be about .250". The supercharger is driven through a splined quill-shaft from the nose of the crank to the bevel gears. This may act as a damper. The carburetter is a big S.U. with a ¼" jet and ⅜" needle. They find they get better acceleration with the float chamber behind. They got excessive richening up otherwise. Probably this is because the S.U. is not of the type where you have an accentuated depression over the jet. They got bad wear of the needle at the bottom end. The supercharger delivers into one end of a plain horizontal pipe along the block. The other end has an adjustable extension which they set to get the distribution a bit better. They use Wilson gear boxes, and have had no trouble at all. The original box in the first car has run all through this season without being looked at. The boxes are made by Siddeleys, not E.N.V.'s. Their only complaint is that they cannot get close enough gears, as they want 1.15, 1.5 and 2 to 1 in the box. Contd: | ||