Air Bleed Adaptor thread size

[The_Softy]

Hi all,

I have a 1986 V8 90 which has a broken air bleed valve between the two carbs (LR Part No. ERC 4820). The bleed valve seems to have coroded intot he hose leaving it blocked and the remaining pipe protrudes 8mm from the manifold. It does not want to budge, after some 27 years I am not surprised. I guess I will need to drill the old one out and re-tap the hole for a new adaptor. Does any one know the thread type of this adaptor?

Thanks

Softy