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Old 06-25-2014, 01:29 PM   #1
Christoph
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Default points do fire....

I have 2 modern type distributors.

One does great and one is eating condensers.

Just put in a new condenser into the "bad" distributor and found,
that it does much more fire, than the "good" distributor.

Tried 5 different condensers and all stays same.

More "fire" on the points of the "bad" distriubutor.
What is wrong?

I thought only way to kill condensers should be bad coil
(with some kind of short inside).

Any ideas ???

Thank you

best regards
Christoph

btw
If i disconnect the condenser, the engine stalls .
I thought it should go on, but points should fire than ???
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Old 06-25-2014, 01:54 PM   #2
newshirt
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Default Re: points do fire....

Is it possible that the 20K volts from the coil is getting to the condenser? E.g. could you have a short or wrong wiring that allows high voltage to enter the condenser? If so, it could exceed the voltage rating of the condenser and burn it out. The burned out condenser could then cause the points to spark and burn.
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Old 06-25-2014, 01:55 PM   #3
Fred K-OR
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Default Re: points do fire....

Christoph, could it be some kind of short in the "bad" distributor? Could the wire that you screw into the distributor from the firewall be going into the "bad" distributor differently than the "good" distributor? This is just my guess and I am no expert.
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Old 06-25-2014, 02:44 PM   #4
Hicktick
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Default Re: points do fire....

When you say modern type , do you have the modern plate with the v8 points ???



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Old 06-25-2014, 03:03 PM   #5
Will N
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Default Re: points do fire....

Think about the routing of the power. It comes to the distributor lower plate though the ignition cable, and makes contact with a bus that is insulated from the plate itself. A wire comes off the bus that leads to the points. The terminal of the condenser also screws into that bus. The case of the condensor goes to ground via the distributor body. The points go to ground via the distributor body.

If the bus were shorted to the lower plate/dist body, you wouldn't be getting any spark at the points at all. In fact, the points would likely get very hot to the touch and you'd be burning out the condenser immediately. Is the condeser making good contact with the bus? Any paint or corrosion on the tab on the bus that the condeser screws to? Is the distributer making good ground to the engine block? Again, any paint or corrosion on the stem of the distributer that goes into the cylinder head?

Last edited by Will N; 06-26-2014 at 07:17 AM.
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Old 06-25-2014, 07:41 PM   #6
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Default Re: points do fire....

You must use the thick insulating washer under the head of the screw that goes into the condenser terminal, and you MUST use the correct length of screw.

If the screw is too long or the insulating washer is missing, the screw will bottom out in the condenser terminal before it's tight, and it will then turn the terminal and wreck the condenser.
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Old 06-26-2014, 04:14 PM   #7
Christoph
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Default Re: points do fire....

Thank you all for your suggestions.

@ Newshirt
No, If 20k Volt would get into the system this would be the case with each Dirstributor
(shortened coil could be the reason)

@ Fred
No - i know the props., you are talkinng about

@ Hicktick
what the vendors call modern style (with condenser on top-plate).

@ Will
It does not make a difference with a different distributor....

@ Tom
Thank you, but i guess you are talking about original-stylwe-condensers.

Will not have time for investigation now , as i will be in hollidays soon.

Thank you
All the Best Christoph
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Old 06-26-2014, 05:12 PM   #8
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Default Re: points do fire....

I think capacitors fail for three basic reasons. (Condenser is the old term for capacitor)
1. Mechanical abuse
2. Heat
3. Exceeding voltage rating

Leads can break off from vibration or mechanical pressure like Tom mentioned. IMO, that is the most common form of failure for modern caps. You get an open circuit because the leads are no longer connected. Some mechanical force has disconnected them, as Tom described. Or maybe you just have a loose connection that only appears solid. The condenser is not even connected to the circuit like you think it is. Or jiggles loose with vibration.

Heat can cause dielectric breakdown and shorts. Not common with modern "shortproof" caps. But it could happen with crap parts.

Exceeding the voltage rating also breaks down dielectric barriers when you get high voltage spikes. I was thinking it might be possible that your "bad" distributor has faulty grounding and a carbon burn path from distributor body to condenser. Or a gap the high voltage could jump. Or both. Faulty grounding could allow high voltage to pass through the condenser instead of straight to ground. Just a wild guess...

Have you tested one of your bad condensers on a capacitor tester? Is it shorted or open circuit? Or is it perfectly good, and the distributor connection to it is faulty?
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Old 06-27-2014, 01:49 AM   #9
Christoph
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Default Re: points do fire....

Thank you Ray
I really appreciate your detailed ideas.

No, im not really able the test capacitors.
I took them out and they are not shorted (at room-temp without voltage)
I just put in new ones and car run again (for 100mls or so)

I will retest the "old" capacitors (which still appear new) in the car.

Direct connections of the capacitor appears perfect to me.
All upper plate appears to be new
Connection of the distributor to the engine looks perfect to me.
(even so i might try a separate ground-cable from the engine to the
distributor and find out if fire at the points will be reduced)

As i had rust-probs with a new style distributor earlier, i will demount
that distributor and will have a look at each component.

Sadly i will have to do some hollidays first (startinng tomorrow),
but i will be back with the outcome for sure !

Thank you
best regards
Christoph
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