Technical Mallory ZC250 questions

So I bought this Mallory dual point ZC250 for my Olds and thought that I should put it in my friends distributor machine to see how it was set up and found that it only had around 4-5 degrees of mechanical advance at around 3000rpm. Consequently, I took it all apart to check it out and to clean it and found that there is a timing stop (for a better word) that is locked down holding the weights in one particular position.
So, not knowing a hell of a lot about these I thought that I would ask you fellas about this. Is this clamp shown in the pic to the right of the arrow suppose to be tight and holding the weights in the position shown? As such there is little room for the weights to do there thing which made me conclude (perhaps not correctly) why I only got so few degrees of mechanical advance.
Is there a way to adjust the amount of advance in these Mallorys? Or how was this distributor designed to work?

 

Doesn't that clamp just hold the point cam in place?

 

CAREFULL THERE !!!!

Thats the rotor index clamp holding the distributor cam in position !!! Shouldnt be moved and if it has been moved the rotor will be out of phase and will need set up on a machine in relationship to distributor cap contact. ( a real pain in the ***).

This unit should have 12 degrees of advance ( thats 24 engine).
Usually these require no adjustment but a really good cleaning and lube.

Carefully remove c clip and distributor plate and cam will lift upward showing the weights etc. Take apart clean and lube..

gladd to help any way i can......

 

Thanks fellas for the input. The hold down did in fact leave a decent witness mark so getting it back to the same spot should not be a problem. I will clean the weights and lube and see where we go from here.