You need a longer long rod if your bow doesnt balance properly......
You may already know this, but your bow should balance on your finger if you hold it around 1" in front of the bushing where your long rod screws in....
Easiest way is turn your bow upside down, put one finger under the long rod and see at what point it balances.... The idea of balancing at an inch in front of the riser is so tht at full draw, when the limbs are bent back and hte centre of gravity moves back, it will be balanced at the throat of the grip.
If your bow doesnt balance, ou can then either add or remove weight on the long rod, or buy a longer or shorter one....
When I started, the long rod length I was recommended in the shop was based on bow length, though I cant remember the details of it.