All engines expand with heat. So cold lash is always tighter. Iron/iron engines need to be .002-.004 tight cold, while iron/aluminum engines need to be .004-.006 tight. Aluminum/aluminum engines need to be .012-.014 tight cold and that may not be enough. You just have to check it.
Remember the pushrods get longer with heat, and so do the valves... most sources I have seen recommend .002 looser than spec lash when cold for iron/iron, but .006 tighter when cold for iron/aluminum...
