I'd love to hear the answer to this too.  I have found many times this same problem, especially when the connector is broken off and i crimp a new one one.

I know that the length of the wire is important i think?  but i would not think that an inch or less would make a difference.

Install the pertronix kit and quit messing with points and resistor wires....

Just my 2 bits.

beaumontguru wrote:

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I know that the length of the wire is important i think? 

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Yes it is, but when I was doing a quick search a while ago, I found it is hard to find an exact answer to this kind of info.  My '64 has no ballast resistor from the factory ... the wire (type/gauge/length) provides the resistance. My wire is not copper in nature.

Someone did a "buckshee" connection on mine a long time ago, and I wanted to look into fixing it. My car starts every time, so, so far I have the "if it ain't broke, don't fix it" attitude, but I'd like to get the proper info. and clean it up in the future.

'64 409 cars used a ballast.

Did they use a ballast on smaller block cars in '66?

seventy2plus2 wrote:

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I'm trying to remember my electrical theory from 30 years ago.  The resistor wire feeding the coil is only a couple ohms, and I wasn't aware it dropped the voltage at the coil to 9v, I thought it would stay at around 12v.  However, the current would be limited.   Putting the key into the start position sends the full current to the starter solenoid, which then sends the full 12v to the coil on the yellow or white wire.

 

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Yes, but I tried it with the key only in "on". There's no point in having the wire from the starter for cranking if the so-called resistor wire has 12 volts in it anyway.

Darryl, I've never seen a ballast on a 66 Chev or Canadian Pontiac yet. At least not a factory installed one.

The head scratching continues....

Just looking at my original 64 cs 409 engine pics and I do not see or remember a ballast resistor on the firewall. When I converted my present 64 to a MSD HEI I replaced the resistor wire from the firewall block with a new wire to run a full 12v to the HEI. The wire replaced is the resistor. The 12v for starting comes through the ignition switch in start position that runs to the starter solenoid. When the car starts the ignition goes to run and the resistor wire comes into play for 9v to the points. So an HEI just needs one 12v wire and the solenoid wire is not needed. You will need to install a wire from the solenoid if you plan to go back to points.
Brian

yes Amps X ohms = the amount of volt drop. If  and open circuit is  zero amps and zero times any ohms is zero so no volt drop. The only way to test a resistor wire is with current flowing through it under a load. It needs to be grounded by the points in order to draw any amps.   My stock 69 has a 1.35 ohms resistor wire a stock coil draws 1.8 amps under idle so 1.35 x 1.8 = 2.43 volt drop   2.43 from 12 volts is 9.57 volts. In the start mode the coil draws around 4 amps so 4 x 1.35 is 5.4 volt drop.  5.4 from 12 volts is 6.6 volts and that why you need the 12 volt additional wire in the start mode from the starter to the coil to get it started.

-- Edited by Beaumont4008 on Saturday 9th of February 2013 11:03:47 PM

its a three wire configuration, they have some type of silver coating

Beaumont4008 wrote:

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I think you still have an open circuit. Try closing the points and then testing. The points need to be closed before a voltage drop will show.

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Now this makes some sense.  As I said above, I was trying to remember my electrical theory.   If you've got an open at the coil end, then yes you will read 12v.  Closing the points will ground the other side of the coil, and I presume then load the circuit, and hopefully provide the desired result.

Magician40 wrote:

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Just looking at my original 64 cs 409 engine pics and I do not see or remember a ballast resistor on the firewall. When I converted my present 64 to a MSD HEI I replaced the resistor wire from the firewall block with a new wire to run a full 12v to the HEI. The wire replaced is the resistor. The 12v for starting comes through the ignition switch in start position that runs to the starter solenoid. When the car starts the ignition goes to run and the resistor wire comes into play for 9v to the points. So an HEI just needs one 12v wire and the solenoid wire is not needed. You will need to install a wire from the solenoid if you plan to go back to points.
Brian

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All the original wiring is still in place. The previous owner simply added an HEI and ran a new wire from the fusebox for a full 12 volts. I am just deleting that wire and going back to the points ignition with the regular coil wired in to the stock harness. I just wanted to test the resistor wire to make sure of the correct voltage because the connection for that wire at the bulkhead was bad. I suspect that is the reason he put an HEI in the car in the first place.

Carl Stevenson wrote:

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I have seen some rear defogger wire harnesses that use what appears to be the same wire. That's how they make low and high speed on some of them. Others use a resistor right on the defogger switch.

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 I used the resistive wire from a defogger when I made an engine harness when I did the 454 transplant into the convertible.

Carl, how did you make out with this?

It's going to have to be running to draw enough load to pull the voltage down... Manually opening and closing the points will only create a draw until the coil is charged which is very quick.

If it is the correct wire it will be fine ie. if 20" of wire drops the voltage down to 9.... 18" of wire will drop the voltage down to 9.2 - 9.3?? You would be hard pressed to measure the difference in point life.

Who's to say it was ever really 9 volts anyway as it depends on load and input voltage.... (rpm, coil draw, temp etc. etc. etc)

If the wire was spliced I would be more concerned by the connection... that stuff is a bear to solder!
Gary