engine knock

I have a 79 firebird with the olds 403 and it knocks after it warms up and only around 3,000-3500+rpm. Any sugestions to weather or not its the bottom end or possibly the lifters? :banghead:

Where does the noice come from bottom or top of the motor????

the heavier the knock the more likely it is that it's coming from the bottom end. you can use a stethoscope (automotive) and kinda locate it.
jake