1924 was a year of firsts for the Sunbeam. It was the year the now familiar
model number system was introduced, and it was on the new overhead-valve
models 8, 9, 10 and 11 that most of the new features were to be found.
The 1924 OHV Model 8 featured overhead valves for the first time on a
Sunbeam. These were controlled by triple return springs.
An EIC magneto was fitted, and an AMAC carburettor. Engine lubrication was
by the Sunbeam-patented fully enclosed automatic dry-sump system. The
standard fuel tank also had an oil compartment, but an optional separate oil
tank could be ordered, giving increased petrol capacity.
A special detachable aluminium silencer could be ordered. To enable the
cylinder head to be removed without taking the engine out of the frame, the
tank tube, complete with tank, could be detached by undoing two bolts, and
to accommodate the straight-through single port head, the frame featured a
bifurcated front down-tube. Marstons called this a “Duplex Frame”! How
seriously these two “improvements” compromised the stiffness of the frame
can hardly be imagined.
This Model 8 also featured, again for the first time on a Sunbeam,
internal-expanding brakes, front and rear. The v-twins had ie rear brakes
from 1914 onwards, and they were also worn by the touring 3 ½ and 4 ¼
HP/Model 7s but never on the front. The more sporting models retained
belt-rim brakes front and rear right up until 1924. The front chaincase was
fully enclosed, as with all other Sunbeam models, but a kick-starter could
not be fitted.