Lister D Amal carburettor threads.

[Boathorse]

Evening all,
I have had to drill out the grub screw that locks off the brass union that the needle valve sits in. I now need to run a tap through the threaded hole in the casting to clean up the thread ready to receive a grub screw from a donor Amal carb. Can anyone confirm what tap I should use in terms of size and thread?
Cheers
Bilmac

[blue cat]

To be honest, I've no idea, having never taken this grub screw out of a Lister D carb. However, I've had a good look at my Lister D carb and there's a little bit of thread protruding on the grub screw. The closest matching tap I could find is 5/16 Whit which, while not definitive, is perhaps not a surprise as the good old Lister D is covered in 5/16 Whit threads. So not a proper answer, but maybe a suggestion to follow up.

Since you have a donor grub screw from another carb, you could check this in a 5/16 Whit die ........

[Boathorse]

Thanks for that Blue Cat, at least your information narrows the field. I am trawling around for imperial taps and dies at the moment, this may take a while but when I have a definitive answer I will post the information here.
Cheers
Bilmac

[blue cat]

Car boots are often a good source of imperial taps & dies for not a lot of money.

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