What does a condensor do exactly?

[714Speed]

What is the condensor's job in conjunction with the points and rotor?

 

[windrider50]

I believe the condensor ( capacitor) acts as a spark suppresor across the point contacts, minimizing the damage uncontrolled voltage arc that occurs when the point contacts open, could induce in the surfaces of the point contacts.

 

[Vettehead Mikey]

The condenser is wired in parallel with the points to reduce arcing across the points as they open. If current is allowed to arc, consistant and precise timing would be difficult to achieve. Equally imporatant, if the points are allowed to arc they will quickly 'pit', reducing their service life.

 

[pauk]

Basically, the condenser keeps the points from arcing, forms a 'tuned circuit' with the coil and provides a path to ground for the secondary of the ignition coil. A point type ignition will not work without it. See enclosed link for more info.
http://www.autoshop-online.com/auto101/ignition.html