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I’ve changed all of the ignition parts (not the distributor). I pulled one of the wires and found no spark to the plugs. The wire coming from the distributor is connected to the negative side of coil and ignition wires are attached to the positive side and the points are gaped at .019. The + side of the coil reads 6.00 volts with ignition switch in the on position and between 8.5 and 9.00 volts while the engine is turning over. My understanding of how the ignition works is as follows:

1. Current flows from the battery to the coil
2. From the coil current travels to the contact points were the opening and closing of the points create a spark.
3. Current is transferred to plugs by the rotation of the rotor as it contacts the post on the distributor cap.


There doesn’t appear to be any current to the contact points. Is there a test for the distributor and coil current flow? I would like to one day change the ignition to an HEI.

I’ve hit a wall

Please Help

Thanks
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by superde69:
I’ve changed all of the ignition parts (not the distributor). I pulled one of the wires and found no spark to the plugs. The wire coming from the distributor is connected to the negative side of coil and ignition wires are attached to the positive side and the points are gaped at .019. The + side of the coil reads 6.00 volts with ignition switch in the on position and between 8.5 and 9.00 volts while the engine is turning over. My understanding of how the ignition works is as follows:

1. Current flows from the battery to the coil
2. From the coil current travels to the contact points were the opening and closing of the points create a spark.
3. Current is transferred to plugs by the rotation of the rotor as it contacts the post on the distributor cap.


There doesn’t appear to be any current to the contact points. Is there a test for the distributor and coil current flow? I would like to one day change the ignition to an HEI.

I’ve hit a wall

Please Help

Thanks
<HR></BLOCKQUOTE>


Okay, to clarify a bit, the stock breaker-points system works like this;

When your engine is running, 12 volts is present in your "IGN" (ignition) circuitry in your car. There is a resistor wire that links the ignition circuitry to the (+) side of the coil. The purpose of this resistor to limit the current, a resistor is what "gives" rather than the coil or the points. A voltage drop results (any current thru a resistor results in a dropped voltage so less is seen at the coil, hence you never see a full 12 volts UNLESS the points are completely open--more on that later). This was done to prolong point contact life. This also saves the coil from becoming a "hot electric stove!" if you were to leave the key in the "on" position without the motor running and the points just happened to be closed allowing current to flow thru the coil at all times.

Back to engine running,

Anyway so current is flowing thru the resitor wire (looks like a funky cloth covered wire) and thru the coil. The (-) side of the coil goes to one of the points contacts. The other contact is always sees ground via the distributor base connected to the engine. When the ground connection of the coil is turned off-on-off-on-off-on-off-on via the opening and closing of the contacts, yes there's a spark that results (unfortunately--that's what wears out the breaker points) but the real purpose is to turn the coil "on and off". If the coil doesn't "see" ground, there's no current path, no current flowing. The coil is an inductor in the simplist sense. The on/off action of a few volts is passed thru a primary winding of fine wire. The electromagnetism in this coil causes a building and collapsing field that causes a high voltage discharge to be produced in the secondary. So now we have the capability of producing BIG sparks from the center plug of the coil to the chassis ground of the car. This now needs to go to the proper place, so the coil wire from the center of the coil to the center of the distributor carries the current. Now the rotation of the distributor takes this high voltage capability and "sends" it via the rotating action to the proper cylinders. Spark, FIRE internal combustion


Now, for the testing, report back on your findings. Take the distributor cap off, have an assistant turn over the engine (give it a few quick cranks.) Make sure the points are OPEN (not touching each other). You should read a FULL 12 volts or more on the (+) side of the coil. Remember, since there is no complete current path due to the open points preventing the coil (-) from seeing ground, there is NO voltage drop. If that reads 12, your okay. IF not, there's other electrical issues in your ignition circuitry.

If it does read okay, turn the ignition off, and disconnect the coil wire, and the wires ALL from the + and - coil screw terminals. Make sure you label things to put them back right. Take an ohm meter and read the resistance across the + and - terminals of the coil. You should see approx. 2 ohms (very little resistance. IF you do not, the coil is garbage.

Post back as there is more to try after you get those results if needed.
 

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It sounds like the points are switching which causes the raised voltage while cranking. This makes me think it's the coil.

You should be able to just turn the distributor body and measure the voltage. When the points open the -ve of the coil will be 12V. When they close the -ve will be 0V. When the points open it should spark if you put a plug and wire right into the coil. The -ve should connect to the distributor and the +ve to the power source.

Just to note. You should have a wire from the small outside post of the starter solenoid to the +ve of the coil so the coil see's a full 12V during cranking. If this wire isn't there the car will still start though. It just gives a better spark for starting.

Peter
 

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Discussion Starter #4
Coopertop,

I did the test you recomended. I pulled the distributor cap and turned the engine over a few times and took a volt reading with the contact points open. The reading was still only about 6.oo volts. No spark is getting past the coil. I even tried running 12 volts directly from the battery to the + side of the coil. Still no luck
 

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remove the condenser and try it again. If it starts replace the condenser. If not replace the coil.

Be sure to leave the negative wire connected to the points. What I want you to do is get the condenser out of the circuit. If it has broken down internally it will ground all or part of your primary voltage. That is fatal to starting a car.

If the condenser proves to be a non problem AND you do have the necesary primary voltage then the only thing left is your coil.

[This message has been edited by charbilly2001 (edited 10-10-2002).]
 

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Charbilly is on the right track,

the next step is the condensor(s). Some cars have 2! One of course is inside the distributor (by the way if you are using "uni-set" points with the built in condenser apart of the points--throw them away and buy the old fashion points and condenser!!)

The other one may be on the outside of the coil. Look for an extra wire that runs to the (+) side of the ignition coil. If you have one and it happens to run to a little cyliner mounted next to the coil, this is a radio noise suppression device. Remove it's lead from the coil as well. Try your results again with NO condensers connected.
 

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While you're in there, look for a short to ground in the wire between the coil and distributor. Since it wasn't really mentioned, the problem is something shorting out the points.

Peter
 
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