Cracked head

wat is the best and easiest way to fix a hairline crack in your head

Get another cylinder head. You should be able to get one from a junk yard for a reasonable price.

I recently picked up a fully rebuilt & ready to install head for a Ford Escort for all of $325. The core exchange was regardless of original head condition. In general, I’d suggest that kind of thing. Lots of machine shops specialize in this kind of service.