Re: blown head gasket
Internally, a blown head gasket will cause no cylinder damage unless water was being admitted. The main thing you need to worry about is if the burning gasses blowing through the bad part burn the mating parts of the head or cylinder liner. Then a new gasket will not seal unless you mill the head or deck the block depending upon which burned.
HOWEVER: If the head gasket was damaged due to detonation, then the piston or cylinder will be damaged and it is not the head gasket cause. SO: if you see a melting piston or a scored liner, it is highly likely that you had/have a carb running lean for whatever reason.
If the liner or head did burn, it will be obvious and you will see the damage. Black discoloration and deposits can be scraped away with a razor.
