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 turning circle, transmission, inlet valve, springs, and chassis details.
| Identifier | ExFiles\Box 180\M4\M4.1\ img009 | |
| Date | 4th April 1922 guessed | |
| Contd. -3- full lock. 5½ lbs. from centre. Dia. of circle to turn Car - Right hand turn 48 ft. 6 ins. Left hand turn 49 ft. 6 ins. Length from centre of sphere to centre of axle - 72½" Slack in transmission. Top gear measured on road wheel 1 3/16" Lean of pivots - N.B. 9/16" O.S. ¾" - measurement taken at 9½' length. Particulars of Inlet Valve. Head 1.98" Stem .3735 Length overall 6.0 Thickness of head .150 (Convex head) Angle of seat 40° Dia. of port 1.843 Two valve springs - Particulars of small spring. Dia. of wire .150 Length 2.525 Outside dia. 1.250 No. of coil 8 Particulars of large spring. Dia. of wire .175 Length 3.200 Outside dia. 1.900 No. of coil 7 Working compression 2⅛". Large spring compressed. 52 lbs. 2⅛" 64 " 1⅞" 80 " 1⅝" 90 " choc-a-bloc Combined spring compressed. 82 lbs. 2⅛" 113 " 1⅞" 130 " 1⅝" 170 " 1⅜" 190 " choc-a-bloc Small spring compressed. 30 lbs. 2⅛" 50 " 1⅞" 70 " 1⅝" 90 " 1⅜" 106 " choc-a-bloc Chassis frame is stamped out to form valences at each side, not the usual U type. Front axle pivot bearing is of one piece and is not supported at the top. | ||