Can i use propane on a butane heater if i change the regulator

If the rating plate on the appliance doesn't say butane...It's not meant for butane! You need to contact the manufacturer of the heater and ask them this question. If you or anyone else gets hurt by this thing, or if you do any property damage with it, insurance isn't going to do a thing for you! you have "altered" the appliance from it's original and intended design. Just because two things fit together doesn't mean they belong together!! There is butane in propane, but butane by itself burns differently than propane. Just changing a regulator is not enough. Orifices and probably the appliance gas valve would need to be changed also...