There is a good chance you did warp it or maybe even cracked the head. But, these engines are hard to fill completely with water, if you didn't have the bleeder on the thermostat housing open you probably didn't fill it with water. When it heats up, does the heater work? If it isn't fairly full, the heater is airlocked and will blow cold. Open the bleeder, fill it slowly and cross your fingers. Even if it is warped, any competent machine shop can surface it as long as it isn't cracked. Mike W.