cleaned the car this morning and gave the engine bay a bit of a polish to and i found what seems to be a bleed valve under the top boost hose which obviously is connected to the amal valve etc,it is fully closed as the engine was rebuilt 700 miles ago although it is boosting at 10psi is this normal and can i use this to adjust the boost safely,not really sure if a bleed valve is basically a boost adjuster as all bleed valves i know of are brass and this one is silver with a blue top ?? any help on this please