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Robert Buchanan

D24 Ignition/Won't start

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Would appreciate any advice on the following situation. 46 D24.  Ran extremely well when I parked it 3 years ago.  Drained gas tank, fuel lines, fuel filter and carb.  Blew out lines and put in new gas.

Brand new battery and brand new coil (previous post re coil).  Coil reading 1.6 on low side and over 8 on the high side.  Power from coil to button on rotor.  Checked and confirmed points at .020.  Power to points.  Distributor, cap, rotor and all internal components are clean and look fine.   No reason to believe timing has changed since car hasn't moved in 3 years.   Won't start.  1.  What's the relationship between the points firing and the coil sending power to the plugs?  2.  Am I correct that power does not run from the points thru the rotor to the distributor?    The only power involved with the rotor and cap is from the coil thru the cap?  Again, I would appreciate any advice.

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The resistance on the low voltage side of the coil should be low. 1.6 ohms sounds possible.  The resistance on the high voltage side should be in the thousands of ohms range.  You reported it as “8”.  8 ohms is far to low, 8 K (thousand) ohms would be reasonable.  What did you measure?   If you pull the hi voltage wire from the center of the distributor and position it near the block while cranking the engine, do you get a fat spark?

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Have you confirmed that you have spark at the spark plugs? 

How it works... When the points are closed they complete the electric circuit for the primary side of the ignition coil. This electrifies the coil and creates a magnetic field. When the points open the circuit is broken and the magnetic field collapses. This induces a secondary voltage that exits via the coil wire into the center of the distributor cap. It then transfers through the rotor to the associated spark plug wire, and up to the spark plug. The electric current then jumps the gap on the spark plug to find it’s path to ground. When all is right this will ignite the air/fuel mixture in the cylinder, things go BANG, and the engine runs... provided it all happens at the correct time, and there is adequate fuel in the cylinder. 

 

 

Edited by Merle Coggins

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the rotor is positioned on the distributor shaft and directs the current of the coil through the cap input center tower to the correct cylinder tower on cap's outer circle of towers...when the points are closed the coil is in saturation and the current is being absorbed into the coil, when the points open, the coil field collapses and produces the high tension spark.....you must ensure that you have power to the coil....then onwards to the points and that the points in turn when closed complete the path to ground....while the points are grounded...you will have no voltage on the distributor side of the coil.....open you will read voltage on both primary lugs...

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46 minutes ago, busycoupe said:

The resistance on the low voltage side of the coil should be low. 1.6 ohms sounds possible.  The resistance on the high voltage side should be in the thousands of ohms range.  You reported it as “8”.  8 ohms is far to low, 8 K (thousand) ohms would be reasonable.  What did you measure?   If you pull the hi voltage wire from the center of the distributor and position it near the block while cranking the engine, do you get a fat spark?

I meant over 8,000 ohms.  I'll see if I can do what your suggesting but might have to wait til I get an assistant.

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44 minutes ago, Merle Coggins said:

Have you confirmed that you have spark at the spark plugs

How it works... When the points are closed they complete the electric circuit for the primary side of the ignition coil. This electrifies the coil and creates a magnetic field. When the points open the circuit is broken and the magnetic field collapses. This induces a secondary voltage that exits via the coil wire into the center of the distributor cap. It then transfers through the rotor to the associated spark plug wire, and up to the spark plug. The electric current then jumps the gap on the spark plug to find it’s path to ground. When all is right this will ignite the air/fuel mixture in the cylinder, things go BANG, and the engine runs... provided it all happens at the correct time, and there is adequate fuel in the cylinder. 

 

 

 

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48 minutes ago, Plymouthy Adams said:

the rotor is positioned on the distributor shaft and directs the current of the coil through the cap input center tower to the correct cylinder tower on cap's outer circle of towers...when the points are closed the coil is in saturation and the current is being absorbed into the coil, when the points open, the coil field collapses and produces the high tension spark.....you must ensure that you have power to the coil....then onwards to the points and that the points in turn when closed complete the path to ground....while the points are grounded...you will have no voltage on the distributor side of the coil.....open you will read voltage on both primary lugs...

OK, i'll test that.  Thanks very much

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your points are basically just a switch to complete the path the ground...the dwell is a manner to express the amount of time the points are closed in the duty cycle (base on 0-100) and that the gap of the points can be set to approximate this duty cycle in degrees of gap expressed in thousandths of an inch...BUT remember any set of  used points that you intend to adjust later should always be done with a dwell meter as surface irregularities due to wear cannot be accounted for with a feller gauge..

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Since the car has been sitting, and you have no spark, perhaps the points have an oxide coating on them.  Try cleaning the points with very fine sandpaper, or better yet, a metal fingernail file.

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They look pretty clean but i'll follow your advice.  Thanks

 

I'm going to have to study the recommendations from a couple of the other guys.  I know enough about the ignition system to get myself in trouble.  I'll see if i can follow the process to check with points both open and closed.

 

Will report back tomorrow, heading out to a BBQ now.

 

Thanks very much for the advice from everyone.

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4 hours ago, Don Coatney said:

Where can a feller get a feeler gauge?🤥

I used to be engaged to one.

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Update.  I cleaned the point contacts and the black wire from the dist to positive side of coil.  POints open with rotor and cap on i get 1.6 across the neg and pos lugs on the coil.

Points closed i get nothing.

 

I also ran  a few other tests.  Points open ground to pos side of battery I get .4 on stationary side of points an 0 on moveable side of points.  I also get .4 on the screw that locks the points in, and .4 on several other screws within the dist.  I get 0 on the black wire at the dist.

Any advise?

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You've compared readings new coil vs. old? New condenser? Good HT and plug wires? With power to the points you should be able to see a spark by opening and closing the points with a screwdriver. 

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Are your posted readings Ohms? I’m having a hard time understanding how you were testing things, but it doesn’t sound right. 

 

Use a test light, or volt meter. (Assuming your car is Positive ground) With the key ON check the voltage at the Neg (-) terminal of the coil. You should see 6 volts. Now test the voltage on the Pos (+) terminal. With the points open you should also read 6 volts. With the points closed you should see 0 volts. 

1. If you have 0 volts at the (+) terminal regardless of points open or closed you need to troubleshoot why the circuit is grounded out. 

2. If you read 6 volts at the (+) terminal regardless of points open or closed you need to troubleshoot for an open circuit.

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Old coil was just above 3 ohms  (3,000) on the 20 scale and the new coil is above 8 ohms (8,000) on the 20 scale on the high side.  Don't remember the reading across the pos and neg terminals (low side) on the old coil but the new one is 1.6 on the 200 ohm scale.  Good plug wires and coil/dist wires.  

1.  What is "HT" that MackTheFingern refers to?

1.  Haven 't tested or checked the condensor.  Is there a way to test it?

 

I'll follow Merles' procedures and report back.  

 

Thanks again.

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HT = high tension ,probably referring to  your wire  connection from center of coil to center of distributor 

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Understand on HT.  Brand new.  

Very encouraging, finally making progress. 

Reading  6 volts at the (+) terminal regardless of points open or closed. 

How and where would I troubleshoot for an open circuit?

 

I really appreciate everyone's help.  This is much better than me fumbelling around in the heat and sweat not knowing what the heck i'm doing and cussing and crying.  My wife just came in and asked me what i'm doing and i explained to her i finally determined i have an open circuit i need to test for.  She called me a genuis.  Do I have to tell her how i figured it out?

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Another verification... Is your + terminal connected to the distributor? From the + terminal of the coil the circuit should ground out when the points are closed. Keep moving your test probe along the circuit. Test at the connection point of the distributor. Then under the cap, test the voltage where the small jumper wire connects to the points. And check again to the body of the distributor to be sure it’s grounding to the engine block. 

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Looks like you have solved your problem. Just a matter of further checking your ohms readings. I think it has already been mentioned ,the distributor points must both close and then open  and if everything is in order,when they open is when the high voltage spark from the coil is generated and then via the distributor cap and the rotor is sent to the spark plugs...I'm a little slow - Merle said it first.😊

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+ terminal is connected to distributor.  When the points are open or closed i have 6 volts at the + terminal on the coil, at the connection point on the distributor, at the small jumper where it connects to the points and on the movable side of the points.  Distributor has a good ground to the block.

Edited by Robert Buchanan

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Check the ohms reading between the movable point(s) in the distributor and the plus terminal on the coil...

Edited by T120
added brackets

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