No spark

[Wahoowins]

1950 Plymouth with factory inline 6. No spark after coil. I have tested  the coil lead to ground and get a good spark with points open and bridging with a screwdriver. No spark from that point forward to any plugs. I'm going to presume the issue is with the distributor but don't know how to test it.  New coil, points condenser, plugs and wires. Points are gapped at .020. No signs of cap cracks. I've had a difficult time finding a mechanic locally who is willing to look at it since it doesn't come with a port for plugging in their diagnostic computer. Any advice on how to proceed with the diagnostics would be much appreciated.

[dpollo]

There is a flexible jumper wire in the distributor which can break or it can ground out due to worn insulation.  That is the first place to look when ignition cuts out.   Replacement cannot be with ordinary wire , it must be super flexible.  

[Merle Coggins]

Double check your cap and rotor. There are a couple different sizes and if they are mismatched the rotor won't pass current through to the cap posts. 

Also, if you pull the coil wire out of the cap and hold it near the block while you open and close the points, with the key on, will you get a spark from the coil wire? This would confirm the coil and points circuit is good. 

[plymouthcranbrook]

Took me two years to find this in my 52 Plymouth. First place I now look if any problems arise.

[Wahoowins]

Thanks, those are great suggestions. I've never heard of the flexible wire before but will certainly look at that first. I had already done the coil test that Merle suggested and it was a strong spark.

[Tom Skinner]

Bump Points around to Rubbing Block to low spot on cam. Leave ignition on.

Now pull points opened and closed with your finger. Are you getting a blue spark at the points?

If not your condenser is bad - new or not.

[Plymouthy Adams]

the fact that  you could generate a spark from the coil by shorting an opens set of contacts proves all but the very surface of the points contacts and their air gap/dwell..if points are old, dress the contacts and re gap...this will serve to troubleshoot but recommend new points if setting long time, they do oxidize

[1949 Wraith]

I had something similar happen to me recently. Car was running great, stopped of at a friends, went to leave and it would not start due to no spark.

I carry spare electrical parts in the car. Started replacing parts till there was only the cap and points left. The cap looked fine and I had replaced the high tension wire and checked for good seating of the other wires. New cap on and she started right up. No cracks or pitted contacts, I figure the central contact spring was old and weak?

It looks like your description every thing was replaced but your cap. It might not be your problem but it solved mine.

[1952B3b23]

I would change the cap, its cheap insurance. Your old one may not look bad but replacing the cap and rotor isn't all that expensive. I believe changing them out was a part of routine tune ups back in the day. I'd also remove the distributor from the car and make a careful inspection of all the wires inside. You could have a bare wire touching something and causing you grief. While you're at it make sure the point gap is indeed .020". I swapped out my points a couple months ago and set the gap to .020". Soon after my car wouldn't start, no spark. I check the point gap and somehow it moved to .035"! It was a good lesson in making sure to double and triple check everything. Good Luck.

-Chris

[Wahoowins]

Dpollo mentioned replacing a flexible jumper wire and worn insulation on it. Went to the local auto parts store and he had a braided jumper wire with no insulation. Is it necessary to have insulation on it? Secondly when I went to install it, I now see that there are actually two jumper wires. The second is clamped to the post where the points spring and screw are and then to the housing. Should these both be the braided wire? 

 

 

 

[Los_Control]

I am actually cheap and bored, I just went through my distributor last week and cleaned everything up and worked on the vacuum advance to get it freed up and working.

The frayed wires, I wrapped with thread to replace the worn cloth insulation, then coated them with finger nail polish to keep the thread glued on.

With the 6 volt positive ground system, it is very important to have the wires insulated.

 

[Merle Coggins]

Yes, the wires in the distributor need to be insulated AND very flexible. The problem with some of the old wires are that the insulation gets frayed and the wires short out against the housing, which shorts out the ignition points function.

[Carl]

    I have a 1950 super deluxe and I am having a time getting spark to the points. I have replaced points and condenser. The lead power in the distributor was broken in half. I replaced it and still no spark. I had some spark before I replaced the broken wire. Should the primary lead from the coil be on the positive side of the coil? 

[Sniper]

19 hours ago, Carl said:

Should the primary lead from the coil be on the positive side of the coil? 

 

Assuming it is stock, the lead from the points should go to the positive terminal of the coil.

 

In an ignition system the primary lead is the one from the coil tower to the distributor, the points are considered part of the secondary side.

 

did you verify the voltage on the coil's negative terminal?  Is it possibe the leaf you replaced is shorted to ground?

[Carl]

    I just took the distributor out yesterday so I could see things better and it looked like the condenser strap was touching the distributor body. I also found in the service manual that I had the wires backwards on the coil. The distributor lead wire is now on positive side of coilI still don’t have fire coil to coil. I have fire on negative side though.

[Sniper]

4 minutes ago, Carl said:

still don’t have fire coil to coil. I have fire on negative side though.

 

I have no idea what you are trying to say here?

[Carl]

Even when I changed the wires on the coil, I still don’t have fire on dis side of coil.

[Plymouthy Adams]

you are grounded.....no voltage can be read....if points are open should read voltage and if not...your lead is going to ground...recheck your work...

 

the 6 volt ignition is just a single wire circuit.  it starts from the battery , ammeter, through the ignition switch, to the coil (you may common share at the horn relay) and then to the distributor where the points are nothing but a switch that turns the coil on and off...when the coil is turned off is where you get your secondary (high) voltage.  Condenser is an arc suppressor and can be shorted...test this also.  

 

the secondary voltage for the plug is routed from the coil output tower to the input of the distributor cap where it is contacts the rotor button that then indexes it to the tower in the cap for the correct plug to be fired...

[Plymouthy Adams]

as an additional so many folks defeat the isolation on the points and when connecting actually are taking their lead direct to ground....ensure you are not doing this...one side of the points is voltage supply from the coil and the other side is direct bolted to ground...this is what makes it a switch via the cam on the distributor shaft.....use your VOM and if you do not have a VOM....you really should get one the HF <10.00 meter will do about anything you need to do checking your car and most all other items at home/shop.

[Carl]

The ground wire in the distributor is connected to the screw that holds the points. Is this correct? I have been trying to find a picture of a distributor so I can check my work. I have a service manual but it do show a good picture.

[kencombs]

3 hours ago, Sniper said:

 

Assuming it is stock, the lead from the points should go to the positive terminal of the coil.

 

In an ignition system the primary lead is the one from the coil tower to the distributor, the points are considered part of the secondary side.

 

did you verify the voltage on the coil's negative terminal?  Is it possibe the leaf you replaced is shorted to ground?

See Plymouthy's post.  the red above is the exact opposite of my understanding.   High voltage is secondary, 12v is primary.  What is the definition in the ignition bible, whatever that is.    Just to clarify the discussion and not confuse me more

[Kilgore47]

These are pictures of the distributor from the 47 P15 when I got it.  There were many things wrong with this distributor.  Some you can see and some you cannot.  The PO said he couldn't keep it running.  Can't believe he got it to run at all.  It's all fixed now.  The problem I want to point out here is at the points.  I you're not carful when the screw for the connections to the points (Number 1) is tightened the spring plate (number 2) can twist and ground out and not fire.  It's easier to remove the distributor to work on it.  Just take a picture before you remove it.  That way you know how to put it back.

[Kilgore47]

This is a picture after it was installed.

[Carl]

Mine is a little different. My condenser has a metal strap instead of a wire. If I took a picture could you check it out?

[Kilgore47]

The condenser in the picture is a copper strap.  Just looking at it from the side in the picture.  Look at the previous pictures and you can see the flat copper strip from the condenser.  The condenser and points are NOS parts.