[hotrod_chevyz]

Sorry to dig up an old thread, but those are called steam holes. They are meant to be there covering them will only hurt. They were put there to prevent pockets of steam inside the engine causing it to overheat. If you have a leak coming from them,Then the head gaskets you used werent exactly right, or you have a difference in years between the heads and block. You might have to use a proper head gasket as a template, and possibly drill additional coolant passages in the block deck or head itself in order to match the heads to the block. if you need some passages covered to fix the leak, you might have to go to a different year or type of head gasket.

T