Jmsanch

40s Deluxe no spark

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I figured I would at least introduce this project, as it goes well beyond no spark.  Not a car mechanic, mostly work on snowmobile, 4 wheelers etc.  I've always wanted to work on an old car, and admittingly this car is a little older then I would like to have started with.  Nevertheless, i jumped at the opportunity fast forward a few months and here I am.  I was told car sat for 10 years to find out when he dropped car off at my house it was more like 31 years.  Given how long it sat i let the cylinders soak in oil for a while.  The engine wasn't locked up, I just wanted to be cautious.   So after a new battery engine spins just fine, compression was low but I sourced a NOS head gasket to replace old gasket.  So which brings me to my original issue.  I'm fairly certain it had the original coil, and we didn't get spark originally.  Confirmed 12v to the original coil.  Replaced the coil and again 12 volts to the coil, and no spark.  So I tried isolating where the issue could be.  Obviously I knew had 12v to the coil, but I wasn't sure the easiest and safest way to test voltage out of the coil.  Thought we could plug a sparkplug directly into the wire coming off the coil ground it out and hope for spark.  No luck.  I did open the distributor cap, and it was really clean.  Nothing looked burnt up, corroded or dirty.  Any suggestions on how to test the coil output? 

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Is this engine a 1940's engine? or has it been updated to using 12 volts? Ether case I would first go into the distributor and make sure the point gap is set right then check the wire that runs from the coil to the distributor to make sure it has continuity and the insulation has not rubbed through and grounding out on the dist. housing. Another possibility is a bad condenser for the points. I'm only guessing because without knowing what your actually working with, I can only assume. If you can give an in-depth description it would be helpful.  Does it have a dual point distributor?  

Edited by retiredmechanic74 (see edit history)

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Yes its a 1940 Pontiac deluxe, engine is a straight 8.  The owner says he always used a 12v battery and never had a problem and at least during his ownership since the 70s has not updated to 12V himself.  So i guess I can assume its a 12v system, and I thought something stepped voltage down to 6v for coil clearly I'm wrong.  I still have the coil that was connected, which looks old and doesn't say anywhere what voltage it is.  So I suppose at this point its safe to assume its a 12v system, and I need to upgrade to 12v coil.  Also supporting this is if I connect an external power source, and give it 6 volts the starter barley moves.  As far as distributor goes I'll need to find out what the point gap is supposed to be for this engine.  I was told this engine ran when it was parked, and hasn't been touched since.  As far as cables go we replaced the dist housing ground wire, and I will check continuity of the the coil to the dist cap tonight.  Visually looks in pretty good condition, but looks can be deceiving.  Finally, there is black box which I think is a transformer, is for 6v accessories in the car?  Let me know if i give you enough info, I can provide pics as well.

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Again a guess. The black box could be the regulator if it has 3 or 4 connections  A picture of the box would tell us.

Edited by GARY F (see edit history)

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Ok here is a pic of the black box, and you are correct it is a regulator.  I included a pic of the distributor, not sure if that helps any

 

image1.jpeg

image2.jpeg

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To start set the points at 15 thousands.  That should be close. With the dist. cap off and the coil wires hooked up have someone crank over the motor, you should see spark at the points. No spark get a good coil.

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I would not assume it is a 12 volt system. In fact I would change over to a 12 volt system so I would know for sure. But check the charging system if it has an alternator then its 12 volts. If a generator check to see what the label (should be an oval plate pop riveted to the housing) has to say. If you can't find anything take the generator off and take it to an electrical shop for verification. None of the auto makers started using 12 volts until 1955 and alternators didn't come into play until 63 or 64 not sure. but anyway with the key on take a test light and hold the points open or put a match cover between the points then check the moving side of the points and you should get a light. If not the points could be grounded out to the dist. plate and the points are no good. If no light remove the wire coming from the coil ( leave it connect to the coil) and  dis-connect it at the points and check the wire got a light bad points no light then there is something wrong with the secondary ign. system. You say you have power to the primary side of the coil so anything from that point on is the secondary system. Hope this helps 

Edited by retiredmechanic74
better explanation for checking power. (see edit history)

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OK if I can chime in, at this stage dont worry too much about the 6v versus 12v, find out why there is no spark;  you will get spark with either voltage.

 

See that white wire coming into the distributor, that carries current form the ignition switch to the contact breakers (points) you first need to determine if you have power at that wire with the ignition turned on, a test lamp or volt meter will quickly establish this.

 

If you have power there, the next thing to do is hand turn the motor to a position where the points are closed, then with the ignition turned on, with a small screw driver manually lever the points open, you should see a small spark at the points, the spark wont be too bright so you may have to throw a cover over the area to keep it dim if you are out in the sunlight.

 

If you dont have a spark at this point you can start by running a piece of emery or fine file between the contact points to make a clean electrical contact surface, if that doesnt work you  need to back track through the wiring to find out why; the coil will not produce a spark without this circuit being complete.

 

If you do have a spark at the points then we can move onto the coil wiring, but first do this bit, its the most likely cause of your troubles.

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Wow lots of great suggestions everyone thanks.  Ok I'm to start looking at the distributor for any issues suggested above.  I'm old enough to remember a car with a distributor system, but young enough not to ever work on one.  I take that back Senior year of HS late 90s Auto Tech class.  Ok well thats why I took on a project like this.  Back tracking a bit, I know I get voltage to the coil, but is there a way to safetly verify output from the coil, like connecting a spark plug to the end of the wire coming off the coil and grounding it out.  Doesn't the distributor just set the voltage to the individual spark plugs in time with the engine?  Or do I need the condenser to complete the circuit/spark?  I found some information on how to test the coil with a multimeter outside of the car, so I might try that too.  I think a refresher youtube video may be in order.   

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retiredmechanic74  Your trouble shooting advice was very good but some of your facts are wrong.  Dodge for one used 12 volts in the teens and twenties as well as some others and 24 volts was also used in that era.

Why would you change a 6 volt system to 12 volts unless you were adding accessories.  6 or 12 volts will do the same work only 6 volts require more amps.

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OK, the trigger to the coil is via the points in the distributor. If you dont have a spark across the points the coil wont fire, whilst you may have power at the coil it needs to flow though the points and back to the coil to create a high voltage spark. So power at the coil is only one half of the solution.

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3 minutes ago, Tinindian said:

retiredmechanic74  Your trouble shooting advice was very good but some of your facts are wrong.  Dodge for one used 12 volts in the teens and twenties as well as some others and 24 volts was also used in that era.

Why would you change a 6 volt system to 12 volts unless you were adding accessories.  6 or 12 volts will do the same work only 6 volts require more amps.

 

Points taken, but here I am just going through the excercise of electrical continuity, it doesnt matter at this stage whether the coil is 6 or 12 volt.

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6 minutes ago, hchris said:

Points taken, but here I am just going through the excercise of electrical continuity, it doesnt matter at this stage whether the coil is 6 or 12 volt.

 

True enough, but what do you guys think is going to happen when the car starts and the generator cutout pulls in? Food for thought....

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For what it’s worth and I’m not 100% sure is the best way to verify. If I switch my battery charger to 6v the starter won’t even turn.  Just hear a hum. As I increase the voltage everything starts to work correctly. 

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Tinindian..... I do agree that some 12 and 24 volt systems where used in the teen years but, by 1955 there were only a handful of car makers left and these are the ones I was referring to. Chrysler settled on using the 6 volt system back (if my memory serves me right, I,m not a historian ) in the 30's and in 1955 changed to 12 volts along with the rest of the industry because a 12 volt system was not as troubling as was the 6 volt system 12 volt is superior for such as starting in cold weather, retaining energy, a wider range of amps and better reliability.  Engines were being made with more compression, more horsepower and a 6 volt starter couldn't handle the changes. Every car I have owned, and there were many, that were 6 volts I changed to 12. ( I lived in Michigan at the time) I think you have guessed by now I'm not an originalist I like chopping up cars and turning them into hotrods and customs but every now and then I let them be themselves.  

Edited by retiredmechanic74
better explanation (see edit history)

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OK plenty of arguments re 6v or 12v; but in the first post as I read it the issue was no spark.

 

Without a spark you wont have to worry about the starter, generator wiring etc.because you cant get the engine to run, so perhaps one thing at a time and as I understand it getting a spark would be the first priority ??

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