timing belt tensioner

I am replacing everything that has to do with the timing belt, but is there supposed to be a spring for the tensioner? If not, how do I tighten the tensioner pulley? Just throw an allen in there and get the belt as tight as I can then tighten it, or what? Because I just bought the timing kit and it didn't come with a spring. I also can't find it anywhere else on the part stores websites