The condenser is a small electrical device connected across the contact-breaker points in the distributor . It helps to give a crisper spark at the plugs and also retards erosion of the contact-breaker points. The condenser, in fact a capacitor, charges while the points are closed. When the points open, the capacitor discharges through the low voltage side of the ignition coil, causing a large change in that magnetic field. This energizes the high voltage side of the coil, and that high voltage is fed to the distributor rotor.
Inspecting and testing the condensor
To test the capacitor with a multimeter, set the meter to read in the high ohms range, somewhere above 10k and 1m ohms. Touch the meter leads to the corresponding leads on the capacitor, red to positive and black to negative. The meter should start at zero and then moving slowly toward infinity.