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).
Specifications for various engine units detailing modifications and components.
| Identifier | ExFiles\Box 155\2\ scan0115 | |
| Date | 13th July 1937 | |
| -2- Rm {William Robotham - Chief Engineer} /Swd1.12/AP.13.7.37 C.15 (22.G.V.) Std. unit other than the following - RR.56. big end bearings and shims. Oil jet holes in connecting rods. Deturbulated head 5.8:1 comp. ratio. Delco governor to suit head. Intermediate main bearings have continuous grooves. Extra hole in each crank journal. Small bore 1 3/8 induction pipe. C.17. Standard production 25/30. unit other than - RR.56 bearing shims. Front 8 water holes between the block and head blanked up. Deturbulated head L.eC.5002 - 5.86 : C/R. Standard valves E.60892 inlet 1.4 dia. E.61073 exhaust 1.225" dia. Modified governor, Bentley frame and 25.HP. spring. Borg & Beck clutch (No.26) 25/30. pistons with L. section 2nd. compression rings. Special hardened timing gears at RRC's request. 6 Rm. {William Robotham - Chief Engineer} 260 springs and 6 EB.256X. C.18 (G.A.L.20) Standard production unit other than - E.61044 exhaust valves, Kl.965 (stell. tips and seats) These are identical in the shape of the head to a reduced Bentley valve, dia. 1.225". EB.175 Bentley valve springs. Exhaust valves later to be replaced by proposed standard. Standard Stromberg induction system and drains with lamp-post vent LeC.5069. Borg & Beck clutch (No.28) 11-A-3. Modified governor, Bentley frame and 25.HP. spring. 25/30. pistons with L. section 2nd. compression rings. Air intake combined with rocker cover LeC.4845. U-7-S (18.G.1V) 20/25. crankcase- non-spread centre, bored out. Whitemetal main bearings. Soft crankshaft with small 2 1/8" dia. main journals. Up-to-date connecting rods with Hall's solid metal big ends. Standard split skirt die-cast pistons E.60632. 20/25. non-turbulent head with .075" packing under the block making the compression ratio 6:1. continued | ||