1939 Will Not Start

[Ramblin Reck]

Turns over fine but will not start. This after putting 1,100 miles on it since August 8, 2021 or 19 months. It quit once on me after turning a corner and I got a tow home. Tried it the next day and it started up with only 7 cylinders as I was testing for spark. That was about one month ago. Yesterday it quit after driving about 14 miles and stopping for a half hour. Started and then quit after I backed up about 10 feet. Would not start yesterday or today when I checked for spark. No spark at a plug.



Hoping it is the coil.
How do I test that?

If not coil, points?
I have never been inside the distributor.

Ya'lls advice always appreciated

[marko39]

Step #1 is to see if you have power to the coil.

[drolston]

If you have battery voltage at the coil, crank the engine to see if the voltage jumps up and down as the points open and close. When the points are open the voltage at the coil should be batter voltage. When the points are closed, the voltage at the coil drops due the voltage loss through the ignition resistor under the dash.



If the voltage stays below battery voltage, you may have bad/shorted condenser. If the voltage at the coil stays at battery voltage as you crank, you will need to get into the distributor to check the points. If you are not willing or able to work inside the distributor, there are people on this site who specialize in rebuilding and calibrating distributors.

[gajeepguy]

If your coil checks bad send it to Skip Haney for a rebuild. Don't even trust a NOS coil. We used to call them 20 minute coils for a reason... -RG

[Ramblin Reck]

Originally Posted by drolston

If you have battery voltage at the coil, crank the engine to see if the voltage jumps up and down as the points open and close. When the points are open the voltage at the coil should be batter voltage. When the points are closed, the voltage at the coil drops due the voltage loss through the ignition resistor under the dash.



If the voltage stays below battery voltage, you may have bad/shorted condenser. If the voltage at the coil stays at battery voltage as you crank, you will need to get into the distributor to check the points. If you are not willing or able to work inside the distributor, there are people on this site who specialize in rebuilding and calibrating distributors.

THANKS TO EVERYONE WHO COMMENTED.

Question on "How To" as suggested by D Rolston in quote: exactly where do I connect the Multimeter? Positive to positive side of coil and Negative to engine block? I have a 12V Positive Ground system.


But before I do that test, could I use one of those spark plug testers(see pic) to check that the coil is "good"? Not sure of what if any precautions I should take if I do this type of test. For example, don't let the other end of the tester ground out on the block?

Tester 12 volt.jpg



I am a real novice at this as I almost burned my grandmother's house down when I was 12 so I have a right to be as nervous as a cat in a room full of rocking chairs!

[Ramblin Reck]

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Originally Posted by gajeepguy

If your coil checks bad send it to Skip Haney for a rebuild. Don't even trust a NOS coil. We used to call them 20 minute coils for a reason... -RG

JawJa Jeep Guy
Did you mean "send the "Distributor" to Skip Haney rather than the "coil"???
Why not just buy a new coil? I may not have not splained that I have a 12volt system, which may or may not have a bearing on this subject. Thanks

[TJ]

First make yourself a "jumper wire" about 5" long with two alligator clips. When the car stops use the wire to bypass the ignition resistor. If it starts up then you have found the problem.

[Ramblin Reck]

Originally Posted by TJ

First make yourself a "jumper wire" about 5" long with two alligator clips. When the car stops use the wire to bypass the ignition resistor. If it starts up then you have found the problem.

Thanks TJ
But can you be more specific as to where I connect the two alligator clips?

[mcgarrett]

If I'm understanding this thread correctly, Ramblin Reck says he has a 12 volt positive ground system. That would render the stock ignition resistor useless wouldn't it? If that's the case, shouldn't he replace the stock resistor with a new one capable of handling 12 volts? But he could still bypass the ignition resistor with a jumper wire to at least confirm if it was good or bad...and resistors do go bad over time.

[47topless]

if he has converted it to a 12 volt system, would he most likely have a 12 volt coil adapter with a built-in resistor? This would be indicated on the outside of the coil can.

[drolston]

Originally Posted by Ramblin Reck

Thanks TJ
But can you be more specific as to where I connect the two alligator clips?

Positive alligator clip to the positive terminal of the coil. That is the wire coming from the ignition switch, not the wire from the coil going to the distributor. The negative lead on the volt meter should go to any ground.


This test is easier with an analog voltmeter; that is, one with a needle rather than a digital read out. The digital ones can be be so jumpy that it is hard to tell what is going on.

[tubman]

Generally, when one of these cars is converted to 12 volts, it is also switched to negative ground. Can the O/P please confirm that his car is positive ground?

[Ramblin Reck]

Originally Posted by mcgarrett

If I'm understanding this thread correctly, Ramblin Reck says he has a 12 volt positive ground system. That would render the stock ignition resistor useless wouldn't it? If that's the case, shouldn't he replace the stock resistor with a new one capable of handling 12 volts? But he could still bypass the ignition resistor with a jumper wire to at least confirm if it was good or bad...and resistors do go bad over time.

McGarrett

YES I DO HAVE A 12VOLT POSITIVE GROUND SYSTEM. I did not convert the system from 6volt to 12 volt. However, I wouldn't know where to look for the ignition resistor on my Flathead

[Ramblin Reck]

Originally Posted by drolston

Positive alligator clip to the positive terminal of the coil. That is the wire coming from the ignition switch, not the wire from the coil going to the distributor. The negative lead on the volt meter should go to any ground.


This test is easier with an analog voltmeter; that is, one with a needle rather than a digital read out. The digital ones can be be so jumpy that it is hard to tell what is going on.

Thanks drolston!

I can follow these instructions. I may even have an old analog(needle type) voltmeter laying around.

[mcgarrett]

Ramblin Reck,
If I remember correctly, it should be under the dash panel attached up high on the drivers' side firewall, north of the clutch pedal. It will look something like this...

https://thirdgenauto.com/product/new...tion-resistor/

[Ramblin Reck]

Originally Posted by mcgarrett

Ramblin Reck,
If I remember correctly, it should be under the dash panel attached up high on the drivers' side firewall, north of the clutch pedal. It will look something like this...

https://thirdgenauto.com/product/new...tion-resistor/

mcgarrett
Thanks

[Ramblin Reck]

Originally Posted by tubman

Generally, when one of these cars is converted to 12 volts, it is also switched to negative ground. Can the O/P please confirm that his car is positive ground?

tubman

CONFIRMED 12VOLT POSITIVE GROUND which was the way it was when I took possession of the car

[Ramblin Reck]

Originally Posted by marko39

Step #1 is to see if you have power to the coil.

NO POWER AT THE COIL!

To test, I connected a test light to the wire coming to the coil from the battery and grounded the other end of the test light. I did not test the wire going to the distributor from the coil. I had the switch "ON" and a friend cranked the engine. What is my next step? There does appear to be a resister attached to the inner firewall, North of the Push Button Starter Switch as suggested in another comment by McGarrett

[Ramblin Reck]

Originally Posted by drolston

Positive alligator clip to the positive terminal of the coil. That is the wire coming from the ignition switch, not the wire from the coil going to the distributor. The negative lead on the volt meter should go to any ground.


This test is easier with an analog voltmeter; that is, one with a needle rather than a digital read out. The digital ones can be be so jumpy that it is hard to tell what is going on.

drolston

I did this test except using a 12v test light rather than a voltmeter and got no voltage at the coil. What's Next?

[rockfla]

Originally Posted by Ramblin Reck

drolston

I did this test except using a 12v test light rather than a voltmeter and got no voltage at the coil. What's Next?

Was the ignition ON when you tested it? IF not then surely there would be NO voltage


OH read two previous post and saw you did!!! Sorry