The over head valve Norton Model 18
was first seen in 1922. The new model retained the
79mm x 100mm bore and stroke that was already synonymous
with the Norton marques 500cc models with the over
head valve top end being fitted to the well developed
Norton bottom end that was already serving the 16H
admirably. Much of the development work on the new
engine was carried out at Brooklands where it established
a new world record for a 500cc class machine covering
a kilometre at 89.22 mph. For the rest of the 1920's
the Model 18 provided the basis for many of Norton's
competition successes. However by the end of the decade,
it, together with the rest of the Norton range were
beginning to look dated, despite the adoption of saddle
tanks in 1929. More Norton
Model 18 information.
