what size is the thread on the fittings that go into the inlet manifold on a cosworth. ie the thread of the blanks and the little hose pipe pieces?

i need to plumb in a 6mm pipe and a 4mm pipe into my inlet, i have a fitting (old bailey one) that screws in, but i need another for a 6mm id vacuum pipe.

can make em at work if i know the threads, unless anyone knows where i can buy these fittings?

cheers