Lister D Fuel tap replacement

What is the size where the tap threads into the larger tank adapter, (is it 1/4inch BSP ?) as even after attempts to bed the tap into the body it still leaks , and I want to replace it with a modern (vintage) motorcycle type (with teflon seals) tap that does not leak.

Are there any better suggestions for replacing the tap for something that does not leak?

If your tap is the original style brass lever tap then bed it in with fine grinding paste and finish off with brasso, then if you are using the right strength spring to keep tension on then it should be fine

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