Actually the larger Cox tank is 8cc and the smaller Baby Bee type is 5cc. The SAM Texaco guys went through all this a while back for the rule change.

That tank sounds pretty small. I'm guessing but at 1 1/8 x 3/4 it's probably only about 1/2 inch thick. That being said this is less than 1/2 oz I would suspect. A minute still sounds short but with the higher nitro fuel it may be right.