PART NO.SPL.PAGEDESCRIPTION
12A1851 Cap nut for pressure relief valve, engine unit, (all MGA)
Tricky bit here is an odd thread specification, 3/4-14-ADM (Admiralty Fine Thread). This is a Whitworth thread form with 55-degree included thread angle, but different thread pitch. But it is sealed with a standard 3/4-inch copper crush washer.
Notice: Moss Motors, Ltd, UK has recently substituted part number 12A1851 for this factory original part.
Tricky bit here is an odd thread specification, 3/4-14-ADM (Admiralty Fine Thread). This is a Whitworth thread form with 55-degree included thread angle, but different thread pitch. But it is sealed with a standard 3/4-inch copper crush washer.