When I make a starbase with just one constructor using one module on turn 17 I am able to add 3 to 6 modules after going economic.
It only seems to stop when there are no more modules and if i stop early there is no ship to eject.
You can add all the modules you want, however they will not actually get BUILT until you supply the starbase with more constructors. This is the new queueing system with 1.7, the idea being you can say "I want all of this stuff!" and send an order out to a nearby shipyard to start making constructors to fill your request.
