No spark except when manually ground coil

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Duster509

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This forum has been a great resource over the years so first, thank you all for your knowledge. I have a 1972 Duster 318, 904, 8 3/4 rear end all in great shape. Sat in someone’s shop since 2000 until I bought it recently. I’m having two issues, the first is that it won’t turn over when in Park, but in Neutral it will. I’m guessing I need to adjust the shift linkage, thoughts?

My bigger problem is that I can’t get any spark. Using my multimeter I have 12v at the battery, and I have 12v at the coil. When I place a spark plug wire with plug on the coil and touch NEG to the intake manifold to ground the coil with scrap wire I get spark at the plug. However when I bump it at the relay I don’t get any spark. What am I missing?

I have new battery, new starter, new coil, new spark plug wires and plugs, new cap, rotor, points, condenser, and ballast. Thanks for any help.
 
What ignition system is installed on the car? The neutral safety could be adjustment but me personally my first step would be to check every ground and ground wire going to engine and body especially if it sat for a long time. The grounds “could” be the cause of both issues. I understand you get spark touching to ground in free air but under cylinder pressure it acts different. Also if it’s mopar electronic make sure the ignition module has a very good ground to its mount or run a designated ground to it. You can run a temporary ground for trouble shooting. The neutral safety could be a worn switch or rooster comb in the transmission. If you don’t have a service manual you can download a free one here.

Service Manuals – MyMopar
 
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Look at the points, the neg wire at the coil goes to the points, when they close it grounds out causing the field in the coil to collapse making the spark at the plug. Either the points arent touching or they are dirty or burnt. You could try cleaning re gapping the points. Touching a wire from the coil neg to ground is mimicking what the points are supposed to do.
 
Possible problem
1..points not set correctly IE not closing, or corroded and not conducting current
2..Internally broken distributor primary wire
3..On some distributors it is possible the advance plate (what moves with vacuum advance) may not be well grounded.
4...Likewise, if you have the distributor clamp loose, the dist. may not be grounded.
 
Not electronic ignition. The points are new so they aren’t corroded or faulty and when I rotate the motor you can see the points opening and closing. The only ground wire I can see is from the battery to cylinder head. Where else should there be grounds? Could the distributor be broken? How would I troubleshoot a distributor?
 
Duster509 said:
Not electronic ignition. The points are new so they aren’t corroded or faulty and when I rotate the motor you can see the points opening and closing. The only ground wire I can see is from the battery to cylinder head. Where else should there be grounds? Could the distributor be broken? How would I troubleshoot a distributor?
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Ok, what do the points look like on a dwell meter?
 
Demonic said:
72 with points? I'm thinking it would be electronic from the factory???
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You're correct, actually. 1972 was the first year for electronic ignition for Chrysler products, but it was the second half of 72. The first half of 72 (which includes back to September 1971) all had points.
 
Duster509 said:
Where else should there be grounds?
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There should be a strap from the opposite head to the firewall, or a second ground to the radiator core support. With the points open, you should have 8 ish volts on them through the coil.
 
Demonic said:
There should be a strap from the opposite head to the firewall, or a second ground to the radiator core support. With the points open, you should have 8 ish volts on them through the coil.
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No you should have whatever the battery is. The coil draws no current with the points open

Points closed: voltage from coil + to ground about 6--10. Voltage coil - to ground, 1/2V the less the better

Points open: Coil NEG and coil POS both the same, full 12V or whatever battery reads
 
One 'contact' of the points has the coil [-] wire attached to it. Get the points open or stick a piece of cardboard in the gap. Measure with an ohmmeter from the points arm to the coil [-] terminal; you should get zero ohms or very close.
Now for the other 'contact' of the points. Measure from the contact to the dist body. Should be zero, if not or high resistance, that is the problem: a poor connection.
 
After looking at the back of the engine I have found a threaded hole for a bolt on the rear of the cylinder head. I’m assuming that is the missing ground from engine to firewall so I will be picking up some cable to fix that ground.

Bewy I will also go test ohms tomorrow. Thanks for the advice so far. Hopefully this solves it and I can update everyone tomorrow.
 
When I was talking about grounding, I was talking about the path through the distributor, which, functionally, is coil neg--through the distributor primary wire and it's end terminals--to the points--to the advance plate---hopefully to the distributor shell, and to the engine block. If it is not grounded, the engine will not crank.

You have already found the LOCATION of the problem--it is "somewhere in the distributor", the points, or the primary wire
 
Duster509 said:
After looking at the back of the engine I have found a threaded hole for a bolt on the rear of the cylinder head. I’m assuming that is the missing ground from engine to firewall so I will be picking up some cable to fix that ground.

Bewy I will also go test ohms tomorrow. Thanks for the advice so far. Hopefully this solves it and I can update everyone tomorrow.
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What I like to recommend for this is to buy a "Ford style" starter cable, that is, no4 or larger "eyelet to eyelet" about a foot--foot and a half. bolt to that rear hole, and be careful of hole depth, and either to a through bolt in the firewall, or maybe on manual brakes, one of the master cylinder studs. Usually there is enough threads to add a second nut. The factory never had such a large ground. Most factory grounds were an anemic about? no 12 or 10 from the battery to the fender. "Not just Mopar" was guilty of this!!!
 
This is my old school way of checking ignition problems. 12v test light and helper needed. Key on, coil + test light on. Coil - light could be on( points open) or off ( points closed). Have someone crank engine. Coil + light on. Coil - light should flash for spark. Light stays on, points not grounding or open wire. Light off, points grounded all the time or wire is grounded. You can also check the wire at the points to find out if the wiring from the coil - to the points is open or grounded. Good luck.
 
Just to chime in. I have a 73 dart sport and it had a similar problem regarding the ability to start in a different gear besides park. Owners before me painted engine and tranny, and they also painted the terminals for the Neutral safety switch. Just in case mine was broken anways, I bought a new NSS. You might have to do the same.
 
ratty dart 340 said:
Just to chime in. I have a 73 dart sport and it had a similar problem regarding the ability to start in a different gear besides park. Owners before me painted engine and tranny, and they also painted the terminals for the Neutral safety switch. Just in case mine was broken anways, I bought a new NSS. You might have to do the same.
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In addition to checking the linkage..
 
Messed around with the Duster tonight and tried bobsgtx method with the light test. When rotating the engine until the points were closed the coil neg stayed lit so the points are not grounding or there’s an open wire. 67Dart273 was correct it’s somewhere in the distributor.

I have put in new points and condenser and even swapped them out for the points and condenser I knew worked in my 68’ Dart. So I guess it isn’t grounding correctly? Is there a way that the distributor is supposed to be grounded? From what I read it doesn’t need to be since it is in contact with the engine block.

I went ahead and took 67Dart273’s advice and ground the engine black from the back of the passenger side cylinder head to the master cylinder as well with 4ga starter cable wire.

This piece below in the picture was on top of the intake manifold near where the coil is. Is this why I’m not getting any spark? Is this some type of ground? What is it? Thanks.

D92F9002-B249-49C7-B710-0E38E5B224D1.jpeg
 
That is a noise suppression capacitor. The wire connects to the coil [+] terminal, slotted piece goes to ground, usually under one of the coil bracket mounting bolts.
 
No, that is your radio supression capacitor/ condenser. It IS a good idea regardless of radio, because it provides a low impedance path for the pulses in the coil, and shunts them to the engine block.

If the condenser in the dist is bad you won't have spark, but you won't have the symptoms you now have.

You should be able to run this down fairly quickly. Do this exactly

With key in "run" and make CERTAIN that the points are in a closed position, ground one meter probe on volts, and probe coil NEG to confirm the problem is still there. You should, if so, show 12V

Now move to the nut connection at the points. You should have 12V there with the problem.. Move to the advance plate in the dist, and see if you have 12V there If not, either the points are gapped too wide and not closing, or the points contacts themselves are oxidized and not conducting current.

If you do, move to the dist. outer housing and see if you have 12V
If you do, somehow the dist is not grounding through the clamp, so try tightening

Hope this is not confusing. When I say "you should have" I was speaking as if the problem exists.
 
Thanks to 67Dart273, I chased it down to the points, they weren’t opening far enough. Is it possible for a distributor’s lobes that open and close the points to wear out? It is extremely difficult to gap the points to .018or even .016 because the lobe seems to be rounded and not as sharp as they should be. Is this possible? Or perhaps I have points that aren’t correct?

Regardless I did my best to get a gap and I had spark when starting the car from the key, so I put the rotor and cap back on to see what would happen. The engine tries to start but it is extremely rough and blows smoke out of the carb. I believe this is because the points aren’t gapped correctly causing rough start/idle. Please correct me if I am wrong. Tomorrow I will get another points from the store to see if that helps.

67Dart273 I see you are from ID. If you are ever in the panhandle especially Bonner or Kootenai county I would be happy to buy you lunch and some beers. Your knowledge is worth gold. Not just from this thread but from hundreds I have read over the years.
 
A small points gap will retard the timing. However, if the points are incorrect for that dist, it is hard to say: could retard, advance or not change the timing.
Points cam could be worn, but I would think most unlikely. If it is worn it is unlikely to affect timing because the spark is generated at the instant the points open, where the least pressure & wear, on the lobes would be likely.
 
I'd like that, if no other reason than to get together. I'm in downtown CDA

A worn dist. cam is not unheard of but I bet it is very rare. Most "wrong" points won't even bolt in. Not sure what to think about that.

A member here, "Halifax Shops" does a lot of distributor/ ignition work, he might know
 
Halifax hops is very knowledgeable with distributors.
Get a test light and follow the voltage.
Good ground to clip alligator to. Key on ,test both sides of coil. Both sides should light if points are open.test contact on points at the coil side. If points are open,test light should light.
Could be wire from coil to points is bad.

With engine turned to close points, the current passes through contacts, test light should not light from distributor side of coil to points.
And there should be an arc if you flick the points.

That being said, the list of stuff that can be overlooked.
Rotor back on, firing order wrong, distributor out a tooth or two, even 180 degrees out.

The points are nothing more than a switch, timed to open with the firing order. Engine should run if gap is .016 or .020
 
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