Misc: Charging Systems Lucas dynamo bolt, please identify thread.

[Tracey Tilley]

Out in Dorset on the bank holiday weekend, the screw fell out of the dynamo on the Comet. Anyone know the thread, please? so Chris can replace it from stock rather than buy one, he's so tight
Lucas dynamo end cap screw. Fits: LUCAS dynamo E3 models from 1936-57, Lucas part number: 103513

 

[chankly bore]

2BA cheesehead screw.