M20 Speedo

[davben23]

Hi I'm on the lookout for a speedometer for my 1949 M20 which has a gearbox driven speedo drive fitted, Does anyone know what the ratio is on this please as I don't want to order the wrong one ?
Thanks Dave

[JulianS]

The Smiths chronometric speedos were listed under a face number not ratio. Only the tachometers had a ratio given.

Below from a BSA parts bulletin issued in 1955 gives the M20 face numbers.