How much slack is allowable for a b-series timing belt before needing to replace or tighten?

Right now, after turning the crank to tighten the exhaust side of the timing belt, the intake side has between 1/4"-1/2" of play. Is that too loose? The motor is not running right now so I can't tell if it flops around while its on.

 

check the front side of the motor, should be 1 inch play or less in the t-belt.

 

that is going to be fine. 1/2 is norm dont worry about it. get the motor running and check it then. the only way it will be more is if your block or head has been machined!