you could do what most everyone else does, drill a small hole in the flange of the Tstat just outside the opening flap, any air in the block finds it's way out that hole to the upper rad hose as the temp comes up, allowing the hot water in the block to contact the stat sensor so it will open .... but if the water in the rad is hot enough to "boil", the Tstat is opening and that's not your problem, especially if it went 5 miles at a fairly steady 130 - air trapped in the block prevents the stat from sensing the water temp and opening.... you also did nothing by filling the rad to the brim except give it more water to throw out as it heated and expanded
you may have a faulty stat, it should not allow the engine to run below it's rating [like that 130], if it's a 160 it won't open until 160 - you also likely don't really know what the temp is if that 130 is what the gauge said, use a laser digital thermoter to check around up front, the stat housing, top and bottom of the rad, front and back of block, and of course the water in the rad and find out what the actual temp is when it's warmed up, you could have a bad/weak water pump or a partially plugged rad, or as is very common with folks used to modern closed systems you are filling it too full, find out what the real temp is, do not depend on an antique gauge that simply shows "cold - hot"
Bill
