Brake Hold off valve
This is a brake question I had because I was having issues bleeding my rear brakes using a new hold off valve I had purchased. On the 70s there is a rear hold off valve used to delay rear breaking and therefore preventing premature rear brake lockup. This is located in the back of the car right before the brake line tees and goes to the rear brakes.
Does anyone know what pressure this hold off valve is supposed to get too before allowing fluid flow and therefore rear brake engagement?