Centaaur gas engine

[Frank Boyle]

Started the piston and again am dogged with chilled cast iron.I took up Grahams advice and put the casting into the fire for hours and then cooled in some kiln dried sand.The chill seems to now have migrated to the skirt of the piston and is proving a b*****d to machine.I am using a TC tipped tool
but it isn't cutting well for the first 1/2".I am open to any advice that sugests a solution to this problem.The only  alternative I can think of is to get a piece of bar and start again.This I don't want to do if I can avoid it.
Frank