As Bundy says. All the original bolts and nuts in the Series 1 will be BSF for fine threaded bolts and Whitworth for coarse threaded ones, except for small screws which are BA. There are a few bits with strange threads such as the plug in the head for an electric block heater - I can't remember what it is, and there are a few BSP.
Be aware though that it is likely that after this time many bolt/nut sets are likely to have been replaced with UNF or possibly ISO, and a lot of parts where assemblies have been replaced with those from later models will have UNF or (rarely) ISO. Contemporary accessories could be any of the above, later accessories are usually ISO.
Whitworth should be fairly readily available, but there are not many of these. BSF and BA do exist, but can be hard to find the exact size you want - worth trying a long established fastener specialist or long established auto parts place.
As noted, the original fasteners are mostly sherardised, which is where the surface of the material is alloyed with zinc by heating (below the melting point of zinc) it in an airtight container packed with zinc dust. It has the advantage over galvanising that the dimensions are unchanged.
John
JDNSW
1986 110 County 3.9 diesel
1970 2a 109 2.25 petrol
Bookmarks