points failure
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
1 thing you may want to look at, there is a resistor wire that reduces voltage to the points to about 9 volts. The purpose is to keep the points from burning. Chrysler cars used the infamous ballist resistor. GM cars used this resistor wire. If the wire were to fail, I would suspect you would have no voltage to the points, but if a previous owner didn't know the purpose of the resistor wire and it failed, and just used any old primary wire, well then you would be burning up points.
I mention this because my 72 had a ballast resistor sitting on the firewall and inline to the distributor. I didn't understand why this part was there, until I learned of the resistor wire and it's purpose. I guess mine had failed at some point and someone at least found a remedy to the situation.
I mention this because my 72 had a ballast resistor sitting on the firewall and inline to the distributor. I didn't understand why this part was there, until I learned of the resistor wire and it's purpose. I guess mine had failed at some point and someone at least found a remedy to the situation.
Please read the Ignition sticky for the function of the ballast.
Thread Starter
Instructor
Joined: Sep 2007
Posts: 244
Likes: 3
From: Long Island
1 thing you may want to look at, there is a resistor wire that reduces voltage to the points to about 9 volts. The purpose is to keep the points from burning. Chrysler cars used the infamous ballist resistor. GM cars used this resistor wire. If the wire were to fail, I would suspect you would have no voltage to the points, but if a previous owner didn't know the purpose of the resistor wire and it failed, and just used any old primary wire, well then you would be burning up points.
I mention this because my 72 had a ballast resistor sitting on the firewall and inline to the distributor. I didn't understand why this part was there, until I learned of the resistor wire and it's purpose. I guess mine had failed at some point and someone at least found a remedy to the situation.
I mention this because my 72 had a ballast resistor sitting on the firewall and inline to the distributor. I didn't understand why this part was there, until I learned of the resistor wire and it's purpose. I guess mine had failed at some point and someone at least found a remedy to the situation.
Thread Starter
Instructor
Joined: Sep 2007
Posts: 244
Likes: 3
From: Long Island
1 thing you may want to look at, there is a resistor wire that reduces voltage to the points to about 9 volts. The purpose is to keep the points from burning. Chrysler cars used the infamous ballist resistor. GM cars used this resistor wire. If the wire were to fail, I would suspect you would have no voltage to the points, but if a previous owner didn't know the purpose of the resistor wire and it failed, and just used any old primary wire, well then you would be burning up points.
I mention this because my 72 had a ballast resistor sitting on the firewall and inline to the distributor. I didn't understand why this part was there, until I learned of the resistor wire and it's purpose. I guess mine had failed at some point and someone at least found a remedy to the situation.
I mention this because my 72 had a ballast resistor sitting on the firewall and inline to the distributor. I didn't understand why this part was there, until I learned of the resistor wire and it's purpose. I guess mine had failed at some point and someone at least found a remedy to the situation.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Melting Slicks
Joined: Jun 2006
Posts: 2,071
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From: S Nevada
And I will quote the Chevrolet service manual, for the 1972 models, chevelle, Camaro, monte Carlo, nova and CORVETTE.
Page 6Y-23. "the primary current from the ignition switch passes through a resistance wire which lowers the voltage to approximately 8 volts. This lower voltage provides for longer contact life." end quote.
Page 6Y-23. "the primary current from the ignition switch passes through a resistance wire which lowers the voltage to approximately 8 volts. This lower voltage provides for longer contact life." end quote.
Melting Slicks
Joined: Jun 2006
Posts: 2,071
Likes: 147
From: S Nevada
Now withouT getting too heavy into electrical theory, namely ohms law, yes the resistor wire does limit current, through our resistor wire, but it's easier to see it with a common garage tool, a multi meter. which you can measure by the voltage drop.
Now doesn't the service manual sound so much easier for the average mechanic to understand? It does for me, 8 flicking volts!
Now doesn't the service manual sound so much easier for the average mechanic to understand? It does for me, 8 flicking volts!
Last edited by Sunstroked; Oct 5, 2013 at 12:32 PM.
Tech Contributor
Joined: Jun 2004
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Now lets get into electrical theory, Ohms law. You cannot measure current flow across the resistor, but you can measure voltage, and amperage, and calculate the resistor needed to drop the voltage. So technically speaking, yes the resistor wire does limit current, which you can see by the voltage drop.
Now doesn't the service manual sound so much easier for the average mechanic to understand? It does for me, 8 flicking volts!
Now doesn't the service manual sound so much easier for the average mechanic to understand? It does for me, 8 flicking volts!
Drifting
Joined: Jan 2006
Posts: 1,832
Likes: 38
From: Cedar,BC
Neither points or condensers are what they used to be. It's been a long time since cars came new with points. As far as I know, there are no USA made points or condensers. In my 64 SS I run a Pertronics electronic conversion for this reason. It's been in there for probably 8 years without a single issue.
If a high quality made in USA point set was still manufactured.I would stick with them,but after two new condensers that failed less than a block from home,and a third set of points fell apart leaving me in the middle of nowhere,that was enough and went to a Pertronics unit and have not had a problem in seven or so years.
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Melting Slicks
Joined: Jun 2006
Posts: 2,071
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From: S Nevada
I'm a design engineer (ignitions and ECMs/PCMs). I'm not inclined to dumb down any of my writings or explanations of things (I don't write fairy tales). The Ignition sticky states how the system actually works. I also wrote it from an enthusiast's standpoint (which I don't believe needs to be dumbed down), as I was a Corvette owner well before I was an engineer. If you see a mistake in the sticky, or have a technical disagreement with the content, please note it and we can discuss it at any length you wish. My point in the sticky was to pass on the knowledge/information I was fortunate enough to receive from many talented and experienced mentors and co-workers, and to sweep away some persistent wives' tales when possible.
Tech Contributor
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From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Perhaps the sticky was "lengthy". I apologize for that. However, I preferred that to a short fairy tale.