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Got the old 560 fired up today after it setting for a couple years. Checked points(cleaned), wires, and so on. After it started it had a bad miss. Started pulling plug wires. Cyl 2 and 5 weren't firing right. Replaced the 2 plugs and it straightened out. So now the big question,......... when you pull the plug wire off just a short distance, enough to get it to arc on a missfiring plug, and the engine smooths out, .....put it back on the plug and it misses again........ can someone explain why
 

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I'll give you my 2 cents. The coil will only put out what is asked of it. When you pull the plug wire off, you are making the the coil work harder. It produces more a intense spark.
 

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Peacher79 said:
I'll give you my 2 cents. The coil will only put out what is asked of it. When you pull the plug wire off, you are making the the coil work harder. It produces more a intense spark.
So if I understand this, the stronger spark forces it way through whatever is shorting the plug out? (plugs were clean so it had to been something inside the plug)
 

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prwttsh said:
Peacher79 said:
I'll give you my 2 cents. The coil will only put out what is asked of it. When you pull the plug wire off, you are making the the coil work harder. It produces more a intense spark.
So if I understand this, the stronger spark forces it way through whatever is shorting the plug out? (plugs were clean so it had to been something inside the plug)
That's pretty much it. It should not be something on the inside of the plug causing the misfire. They may look clean, but could have been gas fouled. There are some plugs made with an auxiary gap inside the plug that is greater then the gap at the tip. In Champion plugs the part # would start with a U. An example would be a UD16. The auxiary gap creates a bunch of RFI, so there are not many of them offered for engines today. Most plugs have some kind of resistor in the upper part of the shell to suppress RFI.Here's a good link to help you see what I'm poorly explaining.http://firetrucksandequipment.tpub.com/ ... -1_615.htm
 

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Many many thanks. You explained pretty close. I'm gonna have to go now and see what the number is on them. Again...MANY THANKS sir. :D :D
 

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Another problem with point igntion is that it seems to cause the suppression core wires to break down quickly, i usually put wire core s on point ignition.
 

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Discussion Starter #7
Let me throw a twist on this now. What about a mag? Is it going to act ther same as a coil and point when it comes to holding the wire away?
 
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