built between 1936 and 1938 is an
updated version of the 20/25 with larger engine to provide more
power, as often, over-large bodies had been fitted to the earlier
model leading to complaints about its performance.The in-line 6
cylinder, overhead valve, engine is similar to that used in the
20/25 but increased in capacity to 4257 cc by increasing the bore
from 3.25 inches (82.6 mm) to 3.5 inches (88.9 mm) with the stroke
remaining at 4.5 inches (114.3 mm). The compression ratio is 6:1. A
single proprietary Stromberg downdraught carburetor replaced the
Rolls-Royce one and magneto ignition was no longer fitted but a
standby coil was provided. The four speed gearbox is mounted in unit
with the engine and a traditional right hand change used.
Synchromesh is fitted to third and top gears.
The riveted chassis has rigid front and rear axles suspended by
half elliptic springs with hydraulic dampers. Braking is on all four
wheels assisted by a mechanical servo, famously under license of
Hispano-Suiza. Separate rear brakes are fitted for the handbrake.
The traditional Rolls-Royce radiator with triangular top was used
with vertical louvers, the angle of which is controlled
thermostatically to control engine cooling.
