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).
Proposals for modifying the 20 HP cylinder for the India Chassis, detailing four different options.
| Identifier | ExFiles\Box 106\5\ scan0020 | |
| Date | 15th March 1928 | |
| R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. to BJ. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} 45060 E1/M15.3.28. INDIA CHASSIS. X.5770 X.5000 X.5050 X.5060 Owing to the position of the foremost and rearmost cyl. studs on the centre line of the engine, the present studs limit the dia. of the valves to 1.3 and 1.2 inlet and exhaust respectively, as against the std. 1.2 interchangeable. By a slight alteration to the pattern, which would not spoil the interchangeability of the casting, these end studs can be pushed out .050, and larger valves of 1.350 and 1.250 then become admissible. These latter valve dias. you have approved. No other alteration to the stud positions is required. The possibilities of modifying the present 20 HP. cyl. may be presented as follows :- PROPOSITION 1. Aluminium turbulent head of present 20 HP style with 1.3 inlet and 1.2 exhaust valves, present gass passages, and to suit the present cyl. block and crankcase unaltered. The exhaust pipe would be somewhat improved in shape PROPOSITION 2. Alum. turbulent head of present 20 HP. style with 1.35 inlet and 1.25 exhaust valves, present gas passages, and with end studs moved out .050, requiring small modification to cyl. block and crankchamber. PROPOSITION 3. Alum. turbulent head of EAC.10 pattern, with 1.35 inlet and 1.25 exhaust valves, larger gas passages, slot weir type induction pipe with water heating only, integral with cyl. head and block, all as shewn on LeC.2527. Suits existing crankchamber with slight alteration as in proposition (2), but requires new cyl. block. Utilises existing valve gear in crankcase by inclining push rods .025 sideways to suit eccentricity of valve centres. New rockers are required to suit the small & centre distance between valves. Ignition tower dropped .875" by shortening drive. This is required to clear No.1 sparking plug. PROPOSITION 4. Same as proposition 3., but with induction pipe uptake separate from cyl. block and having a separate jacket as on EAC.10. This requires the carb. to be moved out and up over the top of the steering box with the present pattern of instrument | ||