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1969 Mustang Convertible 302 T5
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Discussion Starter #1
I have a 302 with a pertronix III distributor with maybe 1500 miles on it. The car ran very well. The other day when I lifted the cap, I saw this. It black/silver dust and attracted to a magnet. Is it metal or is carbon? I don't see any witness marks or anything mechanically damaged although the rotor tip looks a little worn (i.e. detonation). Is this common?
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I don't think that's normal at all and it will probably lead to misfires or electronic interference.
 

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What does your center contact button look like on cap?
 

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Carbon does not stick to a magnet. Ferris metal does. I pop the distributor and disassemble to see where the metal is coming from.
 

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Does your cap have a vent?
Using small diameter cap?

Just looked at my Duraspark and my TFI distributors.
Both have similar but not like that.
I have large diameter on both.
The metal is from the rotor tip vaporizing.
Then it deposits throughout the cap and on plug terminals.
Guessing traces on cap as well.

Clean it up and monitor for now.
Make sure good contact between rotor and center of rotor.
 

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Discussion Starter #7
I don't think that's normal at all and it will probably lead to misfires or electronic interference.
I agree with that. Probably like an electrical storm in there. The car does run really well - but now maybe it will run even better.
 

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Discussion Starter #8 (Edited)
Carbon does not stick to a magnet. Ferris metal does. I pop the distributor and disassemble to see where the metal is coming from.
Isn't the distributor body sealed at some point? The base plates and mechanicals are above the seal. I don't see anything wearing there either. I sent an email to Pertronix so we'll see what they see. To add to this: The dust was really fine powder. Not shavings.
 

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1969 Mustang Convertible 302 T5
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Discussion Starter #10
Does your cap have a vent?
Using small diameter cap?

Just looked at my Duraspark and my TFI distributors.
Both have similar but not like that.
I have large diameter on both.
The metal is from the rotor tip vaporizing.
Then it deposits throughout the cap and on plug terminals.
Guessing traces on cap as well.

Clean it up and monitor for now.
Make sure good contact between rotor and center of rotor.
No Vent. It's a "stock look" cap so I'm going to say that is a small diameter.
I was thinking that the center button on the cap looked a little lacking in size.... is this a possible wear point?

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As long as you have good contact, no problem.

I had one cap where center didn’t appear to be set into cap correctly.

Then at a different time, had a rotor where center tab wasn’t straight from manufacture process.

Hopefully nothing is wrong.
Let us know what you find out.
 

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Pull the breaker plate and check that the springs are attached to the advance weights. If the springs are disconnected, the weights will try and saw the distributor in two, and thus the dust.
Ive seen this before.
 

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That material is a fine "dust" of iron oxide pulled from ferrous metal surfaces inside the distributor, such as advance weights, etc., caused by electrical "activity" within the cap (ie. arcing), which is the end result of the high tension spark from the coil finding an easier path to ground than out to the designated spark plug. High ignition secondary resistance, wide plug gaps, poor engine ground(s), worn cap and/or rotor, bad rotor phasing... all can cause this.
 

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Discussion Starter #14
Pull the breaker plate and check that the springs are attached to the advance weights. If the springs are disconnected, the weights will try and saw the distributor in two, and thus the dust.
Ive seen this before.
The springs are attached, I think I can tell without pulling a plate and the car runs good.
 

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Discussion Starter #15
That material is a fine "dust" of iron oxide pulled from ferrous metal surfaces inside the distributor, such as advance weights, etc., caused by electrical "activity" within the cap (ie. arcing), which is the end result of the high tension spark from the coil finding an easier path to ground than out to the designated spark plug. High ignition secondary resistance, wide plug gaps, poor engine ground(s), worn cap and/or rotor, bad rotor phasing... all can cause this.
Thanks for this reply. I am in the process of upgrading old oem style coil and will check everything that you have suggested. I have to read up on rotor phasing. Is that timing related?
 

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Thanks for this reply. I am in the process of upgrading old oem style coil and will check everything that you have suggested. I have to read up on rotor phasing. Is that timing related?
Rotor phasing is convolutedly related to timing.... The ignition secondary is going to fire when the "trigger" (points/Pertronix/hall-effect sensor, etc.) switches the coil primary circuit open and the coil's magnetic field collapses across the secondary windings. Proper rotor phasing is having the rotor at the optimum point for transmission of that spark out to the contact in the cap, The farther away the point of the rotor is from the contact in the cap the larger the air gap needs to be in order to bridge said gap. Typically, rotor phasing involves moving the distributor reluctor in relation to the distributor shaft to obtain proper phasing.
 

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I had the same distributor, and the rubber bumper on the centrifugal advance stop was out of place and being chopped up by the rotating mechanism. There were flecks of rubber all over the inside of the housing below the advance plate. Might be worth a look, especially if you're seeing more centrifugal advance than you expect.
 

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1969 Mustang Convertible 302 T5
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Discussion Starter #18
I had the same distributor, and the rubber bumper on the centrifugal advance stop was out of place and being chopped up by the rotating mechanism. There were flecks of rubber all over the inside of the housing below the advance plate. Might be worth a look, especially if you're seeing more centrifugal advance than you expect.
I will check this out
 

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Discussion Starter #19
I sent Pertronix an email with the photo and to their credit they responded quickly. I guess I don't have any choice but to park the car while I wait for them to refurbish. I also noticed today when taking a ride that I was getting backfires through the exhaust on deceleration.

This was the Pertronix response:


It's hard to say but I'm thinking the mechanical advance is rubbing on the housing down inside the distributor.

Would you be willing to send us the distributor. We take it apart and find the source of the problem. Once the distributor gets to our building we normally have it fixed in 3-4 days.

Let me know and I'll set up a return for you to send the distributor in. We wouldn't charge you for the service since it's has very low mileage on it.

Your Pertronix Team,
 
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