metal portion of distributor cap burns away in no time

I have a mallory unilite distributor on a 440. The metal portion of the distributor cap that passes the charge to the rotor burns up really fast. I would say today it burnt up around 1/4" in a 40 mile drive. Any ideas what is causing this? Would it be the ignition module in the distributor or something else?

It sounds like there is a gap between the rotor tab and the cap button. Is it the correct parts?

make sure the rotor center "tang" has a bit of tension so it compresses a bit when you install the cap down on it. If there is a gap the arcing will burn the surroundings in no time. also you might put a slight bit of dielectric grease on the top of center tip of the brass rotor tang where it contacts the underside of the cap, the area in question. Helps with radio static also. EDIT Morty beat me to it

I think they were the correct parts. The rotor and cap were both mallory. I will order a new cap and make sure there is tension between the rotor and cap. I will also put some of the dielectric grease. I need to order a new cap because the metal has been eaten all the way up into the cap. Thanks for the advice.

Mallory Unilites use to suffer a lot of lights out failures,(the LED failed) usually half way to nowhere Maybe now is the time to switch ignitions to a better more reliable brand and type Is the positive lead to the coil the 12V source and does the negative side goes where it is suppose to If they're reverse it is possible that is causing the problem with your center electrode

I don't think I have the positive and negative reversed but I will double check and make sure that I don't.

I was burning center electrodes in the caps because of a hot MSD ignition running too much spark plug gap.

is this the cap?

http://www.summitracing.com/parts/msd-209m/applications/distributor-model/37-series

is this the rotor?

http://www.summitracing.com/parts/msd-335/overview/

the unilite I have doesn't have a metal portion in the center.
It has a carbon rod.
very easy to break off and arc to the rotor if it is missing.
it will burn out the unilte electronics as well if you leave it like that.

perhaps they changed it since I got mine.

Like this one.


I burned out 3 before they figured out I snapped the center off.