Like Tony? Dude, I have become WAY too predictable lmao.
There are different sounds that come from an engine, adn there is no easy way to teach someone what they are over the internet in text. But with that said, here we go. If the noise is coming from the top of hte engine and sounds like a "clack", then it's most likely a lifter as stated above. However, unlike what was stated, you will NOT need a head rebuild, just replace the lifter.
If the sounds are more like a "clunk" or like hitting the side of the block with a small hammer, then you have spun a bearing on the rods and you need a complete rebuild.
Start the engine up and let the oil circulate around, then pull the dipstick. If you see metal shavings, then your engine is probably toast. If it looks like a chocolate milk shake, then your head or head gasket is toast.
Me personally, I would NOT trust a knocking engine a thousand miles. And with what is out in Texas, which is NOHTING! I definitely would not trust it. If you break down tomorrow, it's going to be close to 100º and that could end very badly for you guys. Worst case, buy a new car where you are. Explain your situation and I'm sure they will help you out, then just leave that sucker in their parking lot lol.
Good luck bro!