Just trying to understand whats was gone wrong but not 100%. I was driving on the highway when it started losing power then it lost all power and was maked some **** noises and poured out black smoke. After doing a compression test, cylinders 1 and 2 had no compression, so made the call to pull everything apart. After pulling the front timing chain cover off I could see the double row chain for the cam gears was just holding on and one side of the chain. So I thought it might be saveable and maybe just jumped a tooth on the sprocket and the valves didn't kiss the piston. So just took the head off and got a nice surprise between cylinders 1 and 2, a fully melted hole through the head, but also looked like the center of 3 and 4 had been passed a bit of air through. But the real question is how haven't the valves hit the piston and there are no markings at all on the valves of pistons, whats happened.