Triple weber manifold vacuum port thread size

[DrKai]

Does anyone know the thread size of the vacuum takeoff on the canon triple weber manifold. I've tried 3/8bsp/ npt both slightly too large

Thanks

Kai 

[DrKai]

It seems the part from the original manifold fits if anyone knows that?

[NonMember]

If it's the same as the four cylinder (Dolomite) ones then I have a spare somewhere.

[DrKai]

I think I've sussed it. Found a listing for 5/8UNF. If that isn't right I may ask if it could be found out. 

Thanks