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8N with No Spark to Plugs

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Russell Huff

03-08-2008 19:30:06

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I have 8n with front mounted distributor converted to 12 volts. I am not getting spark to the spark plug wires.

I have power to the coil � 12 volts. Same voltage to the pig tail on the coil. I get seven volts from the coil on the tang to the distributor cap. I have good contact from the pig tail to the screw with the condenser wire. I have checked for and don�t have a short to the distributor. I have replaced the coil, distributor cap, rotor, points, and condenser. Still no spark to the plug wires. I did a voltage test through the plugs on the distributor cap with the distributor detached but assembled, manually turning the distributor from the rear. Still no spark through the plug on the cap.

Continuity is good through the distributor cap and across to rotor to the no 1 spark plug plug on the cap when the rotor is detached and made it touch both points (distribtor cap point and no 1 plug inside cap).

The only thing that I can think is that the rotor is not making contract with the distributor. But I have replaced the rotor and distributor cap.

One thing, I don�t understand the function of the points and condenser. When I rotate the distributor, the points make and break contact. But I was expecting some action on the coil to distributor lead. A spike in voltage or something. I don�t see any change. Should there be something? What is their purpose?

Any thoughts?

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OKDAD

03-12-2008 13:48:33

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Re: 8N with No Spark to Plugs in reply to j.w. simmons, 03-08-2008 19:30:06

Dunk....At least you're laughing! I'll just go bang my head for a while.

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Dunk

03-12-2008 06:31:40

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-08-2008 19:30:06

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JMOR

03-12-2008 04:42:19

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Re: 8N with No Spark to Plugs in reply to JRB, 03-08-2008 19:30:06

OKDAD said: (quoted from post at 00:03:01 03/12/08) Russ....I have looked back through this post and several have asked you to verify with a test light or meter that the points do in fact OPEN and CLOSE when you crank the engine. Do they????

OKDAD, he said 'thanks for all the good advice', didn't say anything about following it. He said he will "replace the points again". Remember the definition of insanity, "Doing the same thing over & over & expecting different results"? I gave him a completely reasonable & verifiable explanation for the "voltage drop on the tang", but, "I have replaced 3 coils" persists??

Just as has been said, by so many, so many times, "troubleshooting is the methodical, systematic elimination of possibilities, starting with the most likely, easiest to test and moving on to the less likely, more difficult to test".

Others have said, "you can lead a horse to water, but you can't make him drink". Frustrating to all parties I'm sure. What do you do, but keep on pluggin. Does the light blink? We may never know.

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OKDAD

03-11-2008 21:03:01

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Re: 8N with No Spark to Plugs in reply to JRB, 03-08-2008 19:30:06

Russ....I have looked back through this post and several have asked you to verify with a test light or meter that the points do in fact OPEN and CLOSE when you crank the engine. Do they????

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Russell Huff

03-16-2008 12:33:36

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I see, I see said the blind man in reply to OKDAD, 03-11-2008 21:03:01

I misunderstood the intial advice. Thought they were asking for a spark plug wire test. I found the initial recommendation and reply to it with my results. Advice greatly appreciated.

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Russell Huff

03-11-2008 20:14:29

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-08-2008 19:30:06

Thanks for all the great advice. I wish I could say that that I was getting spark now, but can't. I am going back to square one and start by replace the points (again) and move forward from there. Even though my circut tester say no, I keep thinking that I must have a short somewhere. I have tested three coils (original, replacement # 1 and returned and replaced # 2) and still have the voltage drop on the tang. Thanks again. I'll post with results.

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JMOR

03-10-2008 20:00:49

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Re: 8N with No Spark to Plugs in reply to kurtb, 03-08-2008 19:30:06

Russell Huff said: (quoted from post at 22:35:26 03/10/08) I used a timing light originally to diagnos the problem of no spark.

Timing light may tell you 'no spark', but does zilch in telling you 'why' you don't have spark. Gotta make some of those other test/measurements mentioned in thread.

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OKDAD

03-09-2008 20:05:18

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Re: 8N with No Spark to Plugs in reply to Tom N MS, 03-08-2008 19:30:06

JMOR....That is exactly what I was thinking. One measurement with the points open and the other with them closed. But we're making assumptions now.

I suggest connecting the meter to the power connection to the coil and turning the engine over slowly to verify the voltage does change. If it does then Dell was correct and the coil is most likely toast. IMHO

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JMOR

03-09-2008 19:03:52

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Re: 8N with No Spark to Plugs in reply to 8N'r--WI, 03-08-2008 19:30:06

Dell (WA) said: (quoted from post at 00:35:16 03/09/08) Huffie..... ...I like well composed questions with sufficnent descriptions of what you've done, thank you.
Surprizingly enuff, the rotor should NEVER touch the distributor contacts. Them sparkies just jump'em like they do the real gap in the sparkplugs. (iff'n everything is working correctly) Therefore, you should NEVER read continuity from sparkie wire terminal to the rotor. Why? 'cuz its'n OPEN circuit.
Ah yes, points and condenser, mysterious things for ignition illiteratii.
Heres the deal, sparkies only occur when points OPEN. When closed, points DC current (about 3-amps) creates a BIG magnetic field thru the coil primary winding and coil magnetic core. When the points OPEN, the magnetic field suddenly collapses and creates the HIGH volts needed for the sparkies to jump the gap.
The condenser sucks-up excess electrons that would jump-back across the points and BURN them. Why is burned points a bad thing? The "burn" is a resistive corrosion that reduces the AMPS (current) needed to generate the magnetic field to make sparkies sparkle.
You write..... ."I was expecting some action on the coil to distributor lead"..... .yep, when the points are OPEN, you should read battery volts. (in yer case, 12-volts) When the points are closed, you should read about 3-volts, iff'n its a 6-volt coil, about 9-volts iff'n its a 12-volt coil. You probably won't seen much action iff'n yer turning over yer engine by the starter, probably close to battery volts.
You write..... ."I have power to the coil � 12 volts. Same voltage to the pig tail on the coil. I get seven volts from the coil on the tang to the distributor cap"..... ..WHOOPSIE!!!!..... since yer ignition coil is "auto-transformer" (which is a type of transformer design where the primary and secondary are internally connected together) and since the only way to connect to the coil springy-thingy and the coil tang is out in mid-air, your TANG should read the same volts as yer springy-thingy.
Iff'n you reported everything correctly, then yer sparkie problem is..... .are you ready for this??? ..... .BAD IGNITION COIL. The squarecan ignition coil is barely addiquate and doesn't have much a margin for poor contacts and even worse, when used in 12-volt conversions, they tend to OVERHEAT and melt the internal insulative tars.
Hope has answered yer questions. And NO, I don't know how to tell whether you have the OEM 6-volt coil or the modern 12-volt conversion replacement coil. It could be molded into the bakelite just like they do to tell you iff'n made in China or Mexico. Duh..... ...Dell

Hey, Dell, what if he measured the 7 volts when his points were closed? Then a lot of things start to add up, both as far as his 7 volts AND since he seems to see no change in primary as he 'thinks' points are opening and closing, just maybe the springy thingy never leaves ground. Short somewhere in distributor condenser wire, condenser, springy thingy out of position, etc.

BTW, I have two de-potted coils sitting here & both have the primary & secondary tied together at the top screw terminal. Top or bottom, one would see 12v with points open, but with points closed, a top connection measures 12 minus res drop at HV tab (perhaps 7v here), whereas a bottom connection would measure zero under the same conditions.

I know I'm not telling you anything, but might be informative to somebody out there.

My point being that maybe his 7v measurement doesn't condemn his coil??? third party image

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Bill(Wis)

03-09-2008 05:04:24

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-08-2008 19:30:06

Ford N's are notorious for their myriad of mysterious (to most) ignition problems. Peruse the archives here if you have doubts. Some of my most amusing friends not only swear at them but swear by them as well. They all agree on one thing. Buy the best (read that "made in USA") ignition parts you can find. Blue Streak comes to mind.

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OKDAD

03-08-2008 22:57:20

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Re: 8N with No Spark to Plugs in reply to John in Mich, 03-08-2008 19:30:06

Russ....You lost me with "I get seven volts from the coil on the tang to the distributor cap". Do you mean the "coil" under the dash which is really a resistor with a heat shield? Just trying to help here get us on the same page.

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Russell Huff

03-09-2008 05:48:24

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Re: 8N with No Spark to Plugs in reply to OKDAD, 03-08-2008 22:57:20

Nope. I have a front mounted, square coil. On top it has a bolt for incoming power. On the bottom it has two outputs. 1. Pigtail which sends power to the points, condenser, etc. 2. A tang (small flexible curved flat metal piece) which contacts the power input on the distributor cap and provides power to the rotor. Thanks for the reply.

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soundguy

03-09-2008 17:51:19

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-09-2008 05:48:24

Any results on the test lamp test?

soundguy

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soundguy

03-08-2008 21:43:07

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-08-2008 19:30:06

My guess is too wide points gap.. or they nevr open at all. stick a test lamp inbetween the coil and power wire.. it should blink as the distribuitor spins over.

soundguy

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Russell Huff

03-16-2008 12:29:59

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Re: 8N with No Spark to Plugs in reply to soundguy, 03-08-2008 21:43:07

I see, I see said the blind man... I misunderstood your initial advice. I thought you meant test the spark plug wire. I now understand that you meant test power wire to coil.

I put a test lamp between the coil power input and power wire. No light initially (which I think is right unless points were closed), nor blinking when I crank the engine. This indicates points not closing, correct?

I will check this again, but prior to this test, I reset the point gap and traced continuity or lack thereof through the distributor as the points open and closed. In the process, I saw the points opening and closing as I turned the distributor shaft.

I previously verified that the rotor was turning as I cranked the engine.

Seems to me that the next step is to pull the distributor off and check point open and close again. If I understand the functioning of the distributor, power should be isolated until the points come in contact and then there should be continuity to the distributor body, completing the circuit to ground. Is this correct? Any other thoughts?

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soundguy

03-16-2008 16:56:24

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-16-2008 12:29:59

Yep.. if you are not getting lamp.. then either the coil is not seated(front mount only ).. or the points ain't closing..

soundguy

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Russell Huff

03-10-2008 19:35:26

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Re: 8N with No Spark to Plugs in reply to soundguy, 03-08-2008 21:43:07

I used a timing light originally to diagnos the problem of no spark.

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soundguy

03-11-2008 05:51:49

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-10-2008 19:35:26

Has absolutely nothing to do with my question to you about a test lamp. We already know you have no spark.... There is a big difference in a test lamp and a timing lamp. Timing lamp will tell you no spark.. test lamp will tell you if your points are opening and closing.. or are shorted.. etc..

soundguy

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CENTAUR

03-08-2008 21:07:19

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-08-2008 19:30:06

Did you complete the circuit by grounding the base of the distributor when you turned it by hand? CENTAUR

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Russell Huff

03-09-2008 05:50:08

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Re: 8N with No Spark to Plugs in reply to CENTAUR, 03-08-2008 21:07:19

Good thought, but yes I did.

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Dell (WA)

03-08-2008 20:35:16

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Re: 8N with No Spark to Plugs in reply to Russell Huff, 03-08-2008 19:30:06

Huffie..... ...I like well composed questions with sufficnent descriptions of what you've done, thank you.

Surprizingly enuff, the rotor should NEVER touch the distributor contacts. Them sparkies just jump'em like they do the real gap in the sparkplugs. (iff'n everything is working correctly) Therefore, you should NEVER read continuity from sparkie wire terminal to the rotor. Why? 'cuz its'n OPEN circuit.

Ah yes, points and condenser, mysterious things for ignition illiteratii.

Heres the deal, sparkies only occur when points OPEN. When closed, points DC current (about 3-amps) creates a BIG magnetic field thru the coil primary winding and coil magnetic core. When the points OPEN, the magnetic field suddenly collapses and creates the HIGH volts needed for the sparkies to jump the gap.

The condenser sucks-up excess electrons that would jump-back across the points and BURN them. Why is burned points a bad thing? The "burn" is a resistive corrosion that reduces the AMPS (current) needed to generate the magnetic field to make sparkies sparkle.

You write..... ."I was expecting some action on the coil to distributor lead"..... .yep, when the points are OPEN, you should read battery volts. (in yer case, 12-volts) When the points are closed, you should read about 3-volts, iff'n its a 6-volt coil, about 9-volts iff'n its a 12-volt coil. You probably won't seen much action iff'n yer turning over yer engine by the starter, probably close to battery volts.

You write..... ."I have power to the coil � 12 volts. Same voltage to the pig tail on the coil. I get seven volts from the coil on the tang to the distributor cap"..... ..WHOOPSIE!!!!..... since yer ignition coil is "auto-transformer" (which is a type of transformer design where the primary and secondary are internally connected together) and since the only way to connect to the coil springy-thingy and the coil tang is out in mid-air, your TANG should read the same volts as yer springy-thingy.

Iff'n you reported everything correctly, then yer sparkie problem is..... .are you ready for this??? ..... .BAD IGNITION COIL. The squarecan ignition coil is barely addiquate and doesn't have much a margin for poor contacts and even worse, when used in 12-volt conversions, they tend to OVERHEAT and melt the internal insulative tars.

Hope has answered yer questions. And NO, I don't know how to tell whether you have the OEM 6-volt coil or the modern 12-volt conversion replacement coil. It could be molded into the bakelite just like they do to tell you iff'n made in China or Mexico. Duh..... ...Dell

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Russell Huff

03-23-2008 18:29:00

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Re: 8N with No Spark to Plugs in reply to Dell (WA), 03-08-2008 20:35:16

Found it. I had an intermittent ground on the breaker plate. No ground when bench tested, but ground under pressure from the coil pig tail. Replaced breaker plate. Cranked right up.

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Russell Huff

03-09-2008 06:04:13

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Re: 8N with No Spark to Plugs in reply to Dell (WA), 03-08-2008 20:35:16

Thanks Dell. Very informative. I will return the coil as defective. I guess that I had a bad coil and replaced it with a defective one. We will see. Both were 12-volt made in - gasp - China.

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