For many years the only models available from Norton in SV, OHV and OHC formats
• Side Valve
From the earliest single cylinder machines, some of which used engines other than of Norton origins, through to as late as 1954 when the last side valve machines were finally dropped from the list
• Overhead Valve
From the first Model 18 in 1923 through to the ES2 Mk.ll which was offered until 1966
• Overhead Camshaft
Starting with the CS1 in 1928, followed by the Internationals in 1932 and the racing Manxs up to 1963
