Inlet manifold vacuum pipe take off fitting.

[Clive Foster]

Are you sure its 7/16 BSW and not 7/16 UNC. Both are 14 TPI but thread angle is different, 55° for BSW and 60° for UNC. Can be hard to tell the difference on old components. Frequently the wrong one will screw in but not be reliable, especially on something like a cylinder head subject to heating and cooling cycles.

UNF is the norm for 7/16 sensors, plugs et al for UK / USA vehicles so no surprise that BSW / UNC is hard to find.

Blanking plugs and ordinary push on pipe connectors are trivial to make. I rarely bother to even google for odd ball ones as making takes about half an hour from scratch including set up time if I have suitable hex about the place. Say an hour if I only have rounds. Once set up probably 10 minutes or less floor to floor. I have toolroom style machines. Old style capstan, whether proper or an attachment, or new fangled CNC will be way faster.

I'm a little surprised that BCL don't have a tame "old boy in a shed" on call to knock out a few when needed.

Clive