Are you sure you need to change out the timing chain. One way to tell if your chain in worn is let the engine warm up and let it idle. If the idle is glass smooth your timing chain is fine, if the idle speed wonders around a little and the way it wonders is important if it is a smooth up and down it is not the chain, if the idle speed jumps around, with what I call a lumpy idle. By little I mean 100 rpm or less, and you have ruled out other causes then look to the time chain to be a little worn. With a loose chain the valve timing changes just a little causing the idle speed to jump around. In anticipation of the next question yes gear cam drives are cool.