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).
List of 16 engine and clutch modifications for the 20/25 HP Chassis, series 21-G-IV.
| Identifier | ExFiles\Box 5a\4\ 04-page024 | |
| Date | 7th March 1934 guessed | |
| Hs{Lord Ernest Hives - Chair} 20/25 HP. Chassis - 21-G-IV. X 5820 ENGINE. (1) R.R. S.U. type of carburetter, incorporating worm geared type of slow running adjustment - crankcase breather to rocker cover etc. (2) Eccentric mounting for dynamo pinion to provide quieter gear production. (3) Helical gear oil pump - for greater silence. (4) Modifications to balancing cam to provide additional lubrication, hardened camshaft - end play washers - improved crankcase webbing - easier production assembly. (5) Side oil drain in engine sump to give increased ground clearance and greater accessibility. (6) Baffle in bottom half crankcase to prevent loss of oil pressure when braking - a Bentley modification standardised on the last 10,000 miles car. (7) Battery ignition condenser made by the Condenser Telegraph Co - improved performance and reliability. (8) Battery ignition contact arm pivot pin in hard drawn brass and with Tufnol bush in contact arm - to cure rusting and sticking of contact lever. (9) More silent fan - two alternatives are available. (Handwritten: GWH{George W. Hancock - Head Chateauroux}) (10) Larger oil filler. (11) Drilled up steel connecting rods - cheaper production. (Handwritten: STD) (12) Larger balance weights on existing Bentley crankshaft - a greater percentage of balance can be used on the 20/25 because of the lower maximum engine speed than the Bentley. (13) Felt ring at rear end of rear main bearing as Bentley - to prevent oil leaks. (Handwritten: Fitted) (14) (Handwritten note: Clutch ->) Clutch improvements - increased area of friction surfaces - easy adjustment - needle bearings in operating levers - linings secured with bifurcated rivets (to facilitate production). (15) Oillite bush in front engine mounting - as Bentley - to delete lubrication point. (16) Textolite Gears - mentioned in Wor.{Arthur Wormald - General Works Manager}1/R.21.2.34 but not to be incorporated in 10,000 miles test car. | ||