Originally Posted by
ian sibbert
The valve you have circled is a port used to pressurise the coolant circuit, they are made the same dimensions as a tyre Schrader valve TR4, any machinist should be able to make one in alloy for welding to a header tank (as per your pic) or you could buy an aluminium valve from somewhere like Merlin motorsport or Demon Theives and mechanically couple it to the header tank on a flat surface.....
http://www.merlinmotorsport.co.uk/p1...duct_info.html
Thank you for clearing that up
What would be the benifit of pre-pressurising the water system?
I assumed at first it would be used to vent any air or to de-pressurise the system before removing the lid or even to measure the pressure in the system.