A combustion turbine vane assembly is shown having a retainer block mounting each individual cooled turbine vane. The retainer block has a pair of axially extending opposed rails for sliding receipt of complementary engaging opposed rails on the outer surface of the vane shroud. The block defines a cooling air aperture therethrough. The inner surface of the block is supported a predetermined distance from the opposed surface of the vane shroud defining a cooling fluid receiving chamber therein. The separated distance permits controlled cooling air leakage into a space between the block and the outer shroud. The radial walls of adjacent outer shrouds have complementary axial grooves machined therein and a seal member is disposed therein to bridge the gap and minimize loss of the cooling air.