I did a quick search and couldn't find a thread with the same problem I'm having. If there is one, I must have missed it, sorry. So here goes- The car is an 81 Z28. I built an engine for it a while ago, and when I was breaking the cam in, after about 10 minutes, the upper radiator hose blew off. I was in the car when it happened, so I shut it off as soon as I realized what happened. At first, I thought the hose clamp was just loose, so I tightened it up, but the same thing happened again. I noticed that my upper radiator hose had a bend in it that went up higher than the radiator, so I changed it. I also noticed that the thermostat housing didn't have the same angle off of the block as the stock one, so I put the stock one back in. I talked to one of my buddies about it, and he suggested I take the thermostat out and see if it helps. I took the thermostat out, and started the car up again. After about 10 mminutes, both radiator hoses were rock hard so I shut it down before they flew off. I'm going to put the t-stat back in, with some holes drilled in it as some of you guys suggested in someone else's thread. I put a new 13lb radiator cap on it as well. I'm not sure what to check next, and I'm afraid my brand new engine might already be shot. There is no oil in the antifreeze, and there is no antifreeze in the oil pan. The only thing I haven't replaced yet is my radiator- new water pump, hoses, t-stat, radiator cap. Sorry for the long post, but I wanted to give as much detail as I could think of. Someone please HELP!