Engine Fire - Distributor Related - Pics Included

[ekrupa2]

My MSD Cap failed after a few hundred miles...this was before I heard of the rotor contact not making contact with the carbon button. The button itself fell off but it did not disinegrate. When replaced I bent the rotor up and have not experienced any issues and have close to 5000 miles. I bend it up a few times a season to be on the safe side. I remember the arching did create a whole bunch of rust inside the cap.

[Rick Parker]

I think this is all a "stacking" of variables such as Radio Resistant (MSD type) wires, widened spark plug gaps, resistor plugs and dimensions within the cap between the rotor and the cap. If all of these are at the extremes, the electical resistance is magnified and the load is increased dramatically on the coil and secondary ignition system. The weakest item will fail first.

[Bill Wallace]

I have had corrosion problems but no catastrophic failures (yet) with MSD 6AL. I had the car back at Kirkhams for some other work last December and Jeremy Peterson of Kirkham advised me that the inside of the MSD distributor had rust on it.

The car had 1900 miles on it and is stored in a heated, air conditioned garage.

Kirkham put a new cap and rotor on it. I also bought two extra rotors and caps from Keith Craft. I always carry a spare rotor and cap. In addition, I always drive with my fingers crossed, though it slows down one's shifting.

[Rick Parker]

This is what's going on inside the cap:

ionization: The formation of or separation into ions by heat, electrical discharge, radiation, or chemical reaction.

If there is any air gap between the carbon button and the center tang on the rotor, the resistance is increased more and the carbon overheats and breaks down, turning to fragments that are whipped around inside the cap and are Ionized and stick to the various parts inside of the cap.

[Excaliber]

I do not, from checking MY cap often, have much of an ion problem. Perhaps there are some variables, as Rick has listed, that tend to make one vehicle have more trouble than others?

Now that center carbon breaking problem, yeah, I sure got THAT issue!

[Jerry Clayton]

On my race car with MSD 7 I drilled a 1/2 inch hole between every terminal to control the ionazation---otherwise it would run fine one pass and and then break up at the top end on the next pass--

Now---theory vs facts---why does this show up so much on these cars??? as they are generally run at high power levels the amount of spark/voltage/amps to fire these wide sparkplug gaps is more than a general cruiser type car and also the MSD is multi spark so the issue is multiplied. the carbon if not touching sparks pretty bad, and the ion a zation is terrible---burns off the carbon, and the cap is full of ionized particles of whatever you want to call the air inside the cap ---it took me 8 holes to stop it on the pro stocker, on top fuelers people had went to CO2 cooled magnitoes!!!!!

[Mark Brye]

I have the same MSD cap. Mine looks like that after about 500 miles of use. I keep a spare on the shelf and just keep replacing them. Getting tired of it $$$$.

[Zoom This]

Glad to see others are having the same problem I am having. My center electrode carbon ball was left sitting directly on top of the rotor tang when I removed the distributor cap during a tune up a few years back. I called MSD to air my complaint and they sent me a new cap. I have been a little cautious about this happening again but all "seems" to be OK. It is hard to understand this ongoing quality control issue by MSD however. Is there another brand of cap I can purchase??

[patrickt]

Originally Posted by Zoom This

My center electrode carbon ball was left sitting directly on top of the rotor tang when I removed the distributor cap during a tune up a few years back. I called MSD to air my complaint and they sent me a new cap. I have been a little cautious about this happening again but all "seems" to be OK. It is hard to understand this ongoing quality control issue by MSD however.

Did your original cap have the little black venty looking thing you see below?

[kobrabytes]

I just wanted to echo the point about not having a fuel leak in your engine compartment, or anywhere else on your car.

When I first built my car I had a mechanical fuel pressure gauge on my fuel logs. After months of trouble free driving I smelled gas once after a cruse. I hit the power kill switch and jumped out to inspect the engine compartment. I found fuel had been DUMPING out of the broken gauge. I pulled it and put a pipe plug in the hole. I tore the gauge apart to see what exactly failed. A hole had developed in the flat copper expansion tube. The results of this could have been catasrophic!


I do have a halon fire extinguisher that vents into the engine compartment. But that would only work if activated. If it had of been a windy day I may have not noticed and walked away from the car...

Keep things simple, eliminate points of failure, use the best quality parts you can. As we can see from this thread, stuff can happen that could be a really good ignition source!!!

[Blas]

There was a thread I read somewhere that suggested drilling a small hole on the cap and then connecting a small plastic hose (like from a tropical fish tanks clear air hose) from the cap to the engine’s PVC plumbing hose. When the engine is running, you would pull a slight vacuum in the distributor, continuously purging the ozone laden air inside the cap and replacing it with fresh outside air to compensate for the vacuum.
Interesting concept….They make little brass hose inserts for use with compression fittings that fit the small hose that would make a easy connection to the cap.…and even on a damp day, the air in the engine compartment is hot and dry…The newer style MDS caps actually have a vent in them that could be used as a connection point for the hose …Interesting idea…Maybe I should patent it?

[Jerry Clayton]

Sorry Blas, but GM did that mid 1990s

[Blas]

Darn. How about a kids toy that looks like a big round plastic ring. You put it around your waist and spin it around - I'll call it the Hoola-ring?