I adjust mine .002 looser cold. When the engine is hot the lash tightens. If your adjust them on the tight side of spec when cold they get tighter. As long as you aren't too close to zero when hot. You don't want to keep a valve open and burn it.
No, everything EXPANDS with heat. Even cast iron. I’ve never ever seen a cast iron block and head combo loose lash with heat. Never. They grow. Cast iron block and aluminum heads grow more. An aluminum block and heads will grow as much as .020 depending on the how tall the block is.
So you cold lash tight. How much depends on what the block and heads are made of.
