Difference between 16H and model 18/19

According to:
https://drive.google.com/file/d/0B_5ev0g65Xk6MHRjYmt5bkJRdFE/view?resourcekey=0-mFFZkXlUCvGJf1GVj19yvg
Models 1, 16H, 18, 19 and 20 all had frame part number 8810 in 1936. 
It cost £12 - 0 - 0.

... my 1949 16H engine with a Model 18 so can confirm that both fit. The petrol tanks however were different as I discovered after spending hours painting mine only to find it didn't clear the rocker box.

Hi Ian,

   Your tank was probably pre-war, the tele-fork SV and OHV road bikes shared the same tank with the clearance to standardise production. These did change shape and capacity over the years but the bolt fitting centres remained the same.

... Richard, the bike was something of a bitsa anyway.

Which year are you referring to ? Presumably pre-war as that's the only point where the 16H and the 18 and 19 were available at the same time. 

Pretty well all the pre-war Spare Parts Lists are available on-line and show that a common frame was used for the 500cc and 600cc SV and OHV models. 

The only difficulty comes with the WD16H which had a 1" higher ground clearance, obtained by raising the engine. It was produced 1936 - 1939 with frame numbers from the general sequence and from 1939 - 1945 with a "W" prefix but these have often been re-stamped.

The pre-war 500cc OHV engine can be squeezed into the WD frame, but the 600cc cannot. Inevitably, taking account of production figures, WD frames are much more common than the other "Open Diamond" versions.