The top of the cap is embossed (like the rotor) "MSD"

Thanks for the pics, there is no manufacturer's mark in the cap but that doesn't mean is won't be a good product. It does have an ozone vent and with the included instructions to insure the rotor spring is set right shows they are trying to get it right....we'll see.

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This is the CRT cap (with semi worn button):




This is the MSD cap (has a vent):

They are making an attempt to address the mismatched/anything goes ignition parts being sold these days - this is encouraging. Would you post a picture of the inside area of the cap showing the conductive posts and carbon brush?  MSD is cast on the top surface but years ago, the quality manufacturers used to  cast in their "hall mark."  Just curious if MSD has any marking as such in there....

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The MSD rotor arrived yesterday.  There is a tag attached to it to measure and adjust the tang.  I have never seen a spec for tang height, I never bought an MSD rotor before.

Part number for rotor 8467, cap 84333 (black) 8433 (red)

I forgot about Pertronix and all related components. What limits a lot of choices here is it's a mechanical tach vehicle. I have found Pertronix 2 with the Pertronix 1.5 ohm coil works good without resistor.  Eliminating the resistor increased the spark energy significantly.  I'm not at home this week to check my notes. However, if anyone is interested, I would be willing to set those components in motion just to produce some real time current and temperature numbers when I can. Sorry for straying away from the thread because to my knowledge, Pertronix does not offer a tach drive distributor. 

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I agree that the quality of parts, regardless of where they are manufactured, can be hit-or-miss. As far as I know, only the Pertronix 1 uses a coil/w 1.5 ohm resistance and ballast resistor. If using the correct coil & electronic distributor combination that's recommended by the manufacturers, either the part(s) are defective, or they weren't correctly installed.                                                                                                                                                                                                                               Ted Eaton has said that he prefers a .035 plug gap for both points & electronic ignition. A wider gap may provide a hotter, longer spark, but it can also tax components. Ted also recommends the larger distributor caps, but you have to find one that not only fits the distributor but will also not have any clearance issues. My CRT tach-drive distributor for my 55 Tbird came with the small cap. It's still in the box, so I can't comment. The NGK plugs that I intend to use are pre-gapped .039. I will try both as-is and go from there. 

Even though you are dealing with off shore "stuff," it doesn't hurt to try to solve the issues.  Since the carbon brush is failing resulting in a lot of carbon deposits on the inside of the cap, cross fire now becomes a reality causing backfire. Ozone is yet another product generated by the higher voltage which is highly corrosive if not properly vented.  I think it's safe to say the quality of this off-shore stuff is not consistent with some having no issues and yet some folks reporting many problems as you are.  Your coil is one with a low primary resistance and you are running without a ballast resistor. That combination makes for a super hot and very powerful spark. The cap and rotor are more than likely not up to the task like the high quality extra WIDE caps and rotors used by the OEM's before coil-on-plug became standard. If running a small cap then it must be top shelf quality. It was suggested above that possibly since it looks like a GM copy, try following up with that in mind. Otherwise, the ignition system could be toned down some with a coil having a primary resistance of about 1.5 ohms? Maybe by doing that would allow the cap and rotor to live happy.  After all, how hot of a spark do we really need for our build? These are just a few of the many things that come to mind....

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There was another issue that could be part of this problem.  I had a muffler blow out.   My exhaust shop thinks it was from a backfire.......  I wonder if this could have fried the module in the distributor?????
The backfire was pretty loud.  I replaced the timing chain, I left the distributor in the engine while I replaced the chain.  When I went to start it, I heard a loud backfire and I had to re-time the engine.  Once I got it running, it ran very smooth, about the best it's ever run, so I kind of forgot the backfire.

I have a replacement module, I will give it a try tomorrow.

I had this distributor since the end of last summer.  Beside the (half) dead on arrival coil, the car ran well for months without killing the rotor button.  Now these caps will not last a month.