constraining object properties while adjusting spacing between multiple objects

I want to adjust the spacing between a group of objects while retaining the size of the object. Yes I know about align and distribute but this doesn't help as for my project I need to fine tune the spacing between 270 objects. I recall there was a key or series of keys that I could hold while dragging the group of objects to increase there spacing while retaining the objects properties? Any help is much appreciated!