Can't get bolt loose in harmonic balancer!

What is your question?

Tearing this down to replace head gaskets and maybe heads to. Customer got it real hot. Made me a tool to lock the dohc together to lock engine. And cannot get balancer bolt broke loose. Even tried turning wrong way. Just incase it was backward tread. Anybody had this problem? Plus how easy do them heads crack when got real hot.And what size of wrench is head bolts. Looks allen head to me.