A development of the 20/25, the engine capacity was increased to 4 ¼ litres and for the first time the Rolls-Royce carburettor was replaced with a proprietary Solex instrument.
The 20/25 was also available for sale in 1936.
- Production numbers
- 1201
- Year
- 1936 - 1938
- Engine
- 6 cylinders, capacity 4257cc. Separate cast iron block and two-piece aluminium crankcase with detachable cast iron 6-plug head, deturbulated from 1937. Overhead pushrod operated valves. 7-bearing crankshaft with vibration damper. Pressure fed lubrication with relief valve feeding rocker shaft and timing gears. Oil capacity 14 pints.
- Ignition system
- Coil ignition system with standby coil mounted together. Centrifugal advance with hand override.
- Cooling system
- Engine driven water pump and fan. Thermostatically controlled radiator shutters.
- Carburation
- Stromberg downdraught carburettor with accelerator pump. Exhaust heated inlet manifold.
- Fuel
- 18 gallon rear tank with double SU electric fuel pumps. Electric gauge. Low fuel warning light.
- Transmission
- 4-speed gearbox in unit with engine. Synchromesh 3rd and top. Right hand gearchange. Clutch, Borg and Beck type. Open drive propeller shaft.
- Suspension
- Semi-elliptic leaf springs front and rear. Hydraulic shock dampers equipped with Ride Control.
- Brakes
- Internal expanding 4 – wheel operation with independent handbrake on the rear wheels. Mechanical brake servo motor driven from the gearbox.
- Steering
- Marles cam and roller
- Chassis lubrication
- ‘One-Shot’ centralised lubrication system.