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39 Chrysler issue.


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Can't seem to find a new set of points for my 1939 Chrysler Royal.  Odd things happen over the winter.  Drove it, parked it in December. Bringing her out of hibernation this week wouldn't fire over. Power in and out of coil at 6 volts. 6 volts into distributor and too points. No arc when manually opening points. Traded out a spare condensor and replaced the ground wire that looked crappy.  Still no arc across the points.  Cleaned again and nothing. Not even a cough. Can't find points I know I have here unless someone can tell me they are the same from a 46 Dodge. If not, a lead on a nice set would be most welcomed. Everything is listed as Imperial.

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Do you have a voltmeter?  Can you measure the voltage to the engine ground on the coil side of the points when they are closed. Should be zero. With the points opened should be about battery volts, 6.2 6.3v.  Do you have the coil with the battery voltage that connects with a cable from the key?   
 

We can do some resistance checks on the coil if you are comfortable with that.  The primary side of the coil will be low resistance, somewhere around 2 ohms or less on a 6v coil.

Edited by TerryB (see edit history)
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Factory NOS coil power connects to the rear of coil. That has 6 volts. 6 volts leaving coil.  Let me go check quick.  Points closed near zero.  Open above 6.  We can try the checks sure.  Just to be clear.  You want me to check the ground inside the distributor.

 

Checked again.  6 volts into distributor.  Points closed and checking at points ground is zero.  Points open and checking ground is zero. Power is there probe slipped off screw and got some minor little sparking.

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Six volts measured at points moveable arm when points are open, zero volts on points moveable arm when points are closed is how it should be. I assume the close to zero is 0.10v or less.  Where is your ground reference for voltage readings, block, distributor housing?

 

If you pull the coil high voltage line out of the distributor cap and hold it next to ground do you get a spark?  Did you get the screw in connector with your new coil?


 

 

741CD8E6-493F-40F2-9306-901B2CC35F9E.jpeg

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NOS coil is not an Autolite but an AmpCo and it doesn't have the screw in connector.  Used the bolt on the thermostat housing as my ground.

 

Working by myself here and have not checked the high voltage line into cap as you have stated. Only checking with a plug in light between cap and plugs. Let me see if I can rig up something to crank over and check coil output

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Thanks.  The job was made easy as when I pulled the wire out of the cap the end came off so I just ensured a good connection into the coil and stripped some of the bare end off to wire. Reache through the vent window and cranked while dabbing area's across the head. Only ONCE did I get anything and that was at first crank and even then just a dull orange one time shot (Did it in the dark)  Think I will toss the old coil back in and see what happens there. Remembering back it did this to me one other time when I changed plugs and wires and then went away just by cleaning points and rotor and cap. The ground wire in the distributor did look almost broke today when I changed it and fell apart after removing. This after I changed the coil. So perhaps my NOS coil is junk and the old one wasn't.  Think a resistance test on it while I have it out would be good. Just have to remember how to use OHM side of things. It should be 1.5 correct?

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OK, on the old coil checking resistance with OHM set at 20 which is lowest setting it starts at 3 and counts down to one. Checking high voltage outlet it is reading a 3.  I will pull the new one out in the morning and do a comparison.  Maybe I am reading / setting the multimeter wrong but can't read the microscopic directions that came with it..  Setting it on 200 on the ohm scale reads the same as 20.

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Ok, using the meter on the 20 ohm range is good. Stay on that range for the primary (battery side) of the coil.

1. Touch meter leads together, meter should read 0.00 +/- 0.1.

2. Put one meter lead on the connection at the base of the coil and the other on the terminal that goes to the distributor.  Make sure the meter leads are touching the terminals snugly.

3. Read meter, it should be between 1.0 and 2.0 ohms.  

 

The coil needs a good flow of current through it to work. A voltage reading is just part of the diagnosis, a current flow reading is better.  But first make sure battery cables are clean and tight on the battery, the battery ground cable is clean and tight where it attaches to the engine. Same for the battery cable where it attaches to the starter, clean and tight.  Battery needs to be strong and fully charged. I know you are not new at this, just a reminder.

 

Any extra resistance in the coil circuit is going to affect how well it works.  That’s why points contacts have to be clean and the wire from the coil to the points has to be tight and making good connections.  Check the point gap to be sure it’s correct.  

 

A quick crazy idea is to turn the key off and on about 10x. If there is any resistance in the key electrical internal contacts it could limit the amount of current going to the coil.

 

Thats it for now, I’ll be back later today.

 

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The coil resistance on the battery side will probably measure around 1.5 ohms, maybe a little less depending on the accuracy of your meter.  The symptoms of weak spark is often due to the condenser or its connection at the points.  First it’s necessary to make sure all electrical connections are good.

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Tied up with yard work right now.  Checked old coil and it runs down to zero from 3. Swapping probes back and forth gets same result. Still not getting any spark on the high voltage side of new NOS coil and will dig out an extra plug wire and try that with a sparkplug next. Have to get the other cars out of the garage first to blow out the fall winter first.  but need to clean up all connections first.

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That zero doesn’t sound good.  The ignition book I have says with the points closed and the engine not running the current flow through the coil is 5 amps.  To get 5 amps from a six volt system it’s 6v/5A=1.2 ohms. Did you think the old coil was bad because......   Have fun with yard, it’s raining here so outdoor activities today.

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I am thinking the old coil was bad because it was old. Have to check for spark on the new one. The old one looks almost original to the car.  Everything else on it was or is. The winter artic snap we had for 3 days did some weird things to some of the other cars in the unheated barns.  This is the last one to get running for the Spring. My 31 Plymouth had all 4 wheel cylinder blow out from condensation I figure. Had one battery that was new 6 month ago in the fall not take any charge. Had a coil in my 65 Fury split. The best out of the bunch though was my 31 Franklin. Great car. Full choke and 3 cranks and a cough. Half choke and it fired right up and idled down perfectly after sitting 4 months. Started using a different gas treatment. Star Tron enzyme fuel treatment. Once carbs got primed everything down to the weedeater fired right up.

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Extra OT this week so gave up trying to get some time in the garage. Brought home my multimeter from work and re-tested the old coil. Seems the home meter sucks.  Old coil is reading 1.3 ohms. Tested a new Petronix coil and it reading 1.3 ohms. (I do have a complete spare pertronix set up that will fit the car) So now I am leaning towards a crappy coil wire. Have to see if I can make a new one up. Going to pull the NOS coil I changed and reinstall the autolite with screw terminal and make me a new coil wire as well as a new lead wire to the distributor and see what happens. After that new condensor.

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12 minutes ago, Brooklyn Beer said:

Question on installing the coil wire into the screw in terminal.  What is the proper installation of the wire? Stick some bare wire through and just fold it back so it make contact when screwing it in  ?

That sounds familiar, I’m trying to remember how mine looked in my 37 Dodge.  You need to make sure the coil wire does not pull out so using a fold over seems right.

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1 hour ago, Brooklyn Beer said:

so with 6 volt I am looking for non resistor core.

I’m fairly sure resistance wire did not exist back in that time. The resistance wire limits radio interference and radios were not as common. The resistance wire should still produce a decent spark as the theory on how the ignition works remains the same.  The big resistance is the spark plug gap so the resistance wire ohms is minor compared to that.  The coil output voltage is most dependent on good battery volts to the coil, good clean connections to and at the points and a good working condenser. Point gap is important to ensure the coil gets charged up properly. 
 

 I had wire core wires on my 1937 as that was typical of the era. Never had issues with them. 

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In between holiday stuff I tested the coil wire and it shows no drop off in resistance. Taking that out of the mix now. Have a new cap to trade out and condensor. Full voltage to everything with good connections. Then if no spark I am perplexed.  Not messing with points yet as it ran just perfect before I parked it 3 months ago.  Just can't even get a cough. This should not be this difficult to chase down !

 

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I checked this NOS Auto-Lite coil I have with a good digital meter and the primary side, measured from the screw in the base to the top terminal next to the HV tower read 1.2 ohms. I next measured the secondary from the top terminal to the HV tower and got a reading of 5.97K ohms using the 20K ohm range of the meter.  Seems like good readings for a reference.

ABB17131-5DB4-4AC8-BE8A-2577AE0489C6.jpeg

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May I recommend to recheck the coil readings when hot? My 1940 did run well when cold, until reaching normal running temperature then it started failing. Turned out it was not the fuel supply or choke playing up, it was the coil that started failing when it got hot. Replaced it with an Autolite similar to the one displayed and suddenly the car would pull well uphill when hot.

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  • 3 weeks later...

Well I got some time and got back to it. After checking out the existing coil and getting proper readings I reinstalled. I changed out the old condenser and checked gap on points. New cap and rotor. Checked coil wire. Turned it over and fired up and ran nice for about 1 minute then crapped out.  Every once and while I get it to cough and then no spark again. Have it on charge now and have new points to install.  One thing I am seeing with the points besides a dull orange spark when I manually open them (battery) is it doesn't seem to be jumping the gap straight across all the time but down and out, erratic to say the least.  New points are next.  Thought I had it when it fired right over. 

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Posted (edited)

Points. Once I got them out you could really see the problem with the angle on the contacts and pitting.  Cleaned all the connections in the distributor. New points, condenser, cap, rotor. New ground wire in distributor.  Literally fired over on first crank. Miss is gone !

 

 

I like little victories.  Makes for a good day. Really surprised the O'Riellys here had everything.

Edited by Brooklyn Beer (see edit history)
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