1937 Special no spark help

[37Special]

I need some help figuring out why I have no spark. I have an idea but I am no mechanic.  Last week my buick was started and running and a few minutes later it died and would not start again.  Engine turns over but never tries to spark. Gas was added to carb with no change. After checking connections and testing for spark with a light tester I am not getting spark.  I'm guessing something in the distributor.  It has a pertronix ignition and I pulled that and replaced with a set of known good points and coil with no change.  What else do I need to check? Thank you very much for the help! 

[Matt Harwood]

If it's dead with both points and Pertronix, it's probably wiring or maybe the ignition switch. Is the coil getting power with the ignition on?

[EmTee]

52 minutes ago, Matt Harwood said:

Is the coil getting power with the ignition on?

That ^^^  A test light or voltmeter will tell you.

[37Special]

Yes used a voltmeter and getting 6.3 volts at the coil positive and negative leads

[Bloo]

Maybe a broken ground wire in the distributor?

 

Using the points to troubleshoot, do this:

 

With the points open and the key on, check from coil (+) to ground and coil (-) to ground. Both should be about 6 volts, and basically the same.

 

Then, roll the engine over just enough so the points are closed, turn key on,  and check again.

The positive terminal should have 6 volts now, but the negative should have zero or almost zero.

 

If any of that is not as it should be, post back which test is coming up wrong.

 

If all that is OK and you still don't have spark, change the condenser. If that doesn't help, change the coil.

[EmTee]

I'm interested to hear the results from above, given that the initial incident occurred with Pertronix installed.  The common component would seem to be the coil...

[nat]

     Make sure the wire within the distributor isn't shorting inside the distributor and/or where it passes through the distributor housing.   

      Consider the coil itself as a possibility.

[37Special]

Thanks for the quick responses and help all! Just got back into town from the holiday weekend so I'll start tinkering and try these things out. 

[37Special]

On 7/1/2023 at 8:59 PM, Bloo said:

Maybe a broken ground wire in the distributor?

 

Using the points to troubleshoot, do this:

 

With the points open and the key on, check from coil (+) to ground and coil (-) to ground. Both should be about 6 volts, and basically the same.

 

Then, roll the engine over just enough so the points are closed, turn key on,  and check again.

The positive terminal should have 6 volts now, but the negative should have zero or almost zero.

 

If any of that is not as it should be, post back which test is coming up wrong.

 

If all that is OK and you still don't have spark, change the condenser. If that doesn't help, change the coil.

So I finally had time to work on this a bit. Tried this test a d on negative I'm getting. 05 so close to zero.  Still no spark so bought a new coil cap and rotor with no change. Any other ideas? I'm stumped now. 

[Hubert_25-25]

Does the rotor spin when you crank the engine?

 

If you have points, start with turning the motor until the rubbing block of the points is on the high spot.  There should be a point gap.  Pull the coil central wire from the distributor and hold it near the block.  Turn the key on.  Using a screwdriver, cross the points with the tip of the screwdriver.  That should create a spark to the block every time you pull the screwdriver away from closing the points.  

- Point gap should be .016 when on the distributor lobe.   When you roll the engine to the flat on the distributor, the points should be closed and the point surfaces should be flat together.

- Remove the power wire from the coil.  Connect an ohmmeter to the 6 volt coil wire on the distributor, and ground the other lead of the ohm meter to the block.  Rotate the engine by hand to two point settings.  One with the points closed, and the other with the points open. You should have 2 different readings.  If the same reading, then you are perhaps missing an insulator and the points are grounded.  Or there is an open circuit.       

Edited July 15, 2023 by Hubert_25-25 (see edit history)

[Bloo]

This covers it.^^

 

The reading on the negative side of the coil should change when the points open. If it doesn't change like that, there will be no spark because that switching is what fires the coil.

[EmTee]

I wonder whether there's an open (or possibly an intermittent one) between the breaker plate and ground because the issue first arose with Pertronix installed.  Switching to breaker points has apparently made no difference...

[Bloo]

29 minutes ago, EmTee said:

 because the issue first arose with Pertronix installed.

Wait, what? Is that when it happened? If so, I missed that.

 

@37Special, is the ground wire in the distributor still there? Pertronix needs that just as much as the points.

 

[EmTee]

On 7/1/2023 at 6:21 PM, 37Special said:

I'm guessing something in the distributor.  It has a pertronix ignition and I pulled that and replaced with a set of known good points and coil with no change.

First post ^^^

[Bloo]

Oh, but that doesn't mean it stopped working exactly when the Pertronix was installed... does it?

[EmTee]

I don't think so, but the OP doesn't say how long the Pertronix was in use before spark was lost.

[37Special]

On 7/15/2023 at 6:46 PM, Bloo said:

Wait, what? Is that when it happened? If so, I missed that.

 

@37Special, is the ground wire in the distributor still there? Pertronix needs that just as much as the points.

 

Yes it is and looks intact.  I have a new one coming from bobs just in case that's the culprit. 

[37Special]

23 hours ago, EmTee said:

I don't think so, but the OP doesn't say how long the Pertronix was in use before spark was lost.

I had the pertronix in for 2 years before this happened.  

[37Special]

On 7/15/2023 at 1:52 PM, Hubert_25-25 said:

Does the rotor spin when you crank the engine?

 

If you have points, start with turning the motor until the rubbing block of the points is on the high spot.  There should be a point gap.  Pull the coil central wire from the distributor and hold it near the block.  Turn the key on.  Using a screwdriver, cross the points with the tip of the screwdriver.  That should create a spark to the block every time you pull the screwdriver away from closing the points.  

- Point gap should be .016 when on the distributor lobe.   When you roll the engine to the flat on the distributor, the points should be closed and the point surfaces should be flat together.

- Remove the power wire from the coil.  Connect an ohmmeter to the 6 volt coil wire on the distributor, and ground the other lead of the ohm meter to the block.  Rotate the engine by hand to two point settings.  One with the points closed, and the other with the points open. You should have 2 different readings.  If the same reading, then you are perhaps missing an insulator and the points are grounded.  Or there is an open circuit.       

I will try the last part of this and try the screwdriver.  I've done everything else here and no spark when I hold the coil wire to the block but I haven't tried with a screwdriver. Just rolling the engine over. Gap was correct and points are opening and closing properly. I'll try everything else out and see. 

[Bloo]

Be sure the voltage on the negative terminal of the coil is going on/off as you open/close the points. That is a very important detail.

[37Special]

16 hours ago, Bloo said:

Be sure the voltage on the negative terminal of the coil is going on/off as you open/close the points. That is a very important detail.

That part is happening.  Goes from about 6 volts to. 05

[Bloo]

Take the coil wire off at the distributor end and put it really close to some grounded metal (engine block or whatever). Open and close the points. Check for spark this way using only the coil and coil wire. If you have no spark there, or extremely weak spark, try a different condenser. It doesn't have to be a new one and it doesn't have to be the right one for the Buick, but it DOES need to be one that came from an engine that runs. In other words, not one that has already been tried in this Buick that has no spark. If you still do not have spark at the coil wire, the coil has to be bad.

 

Edited July 17, 2023 by Bloo (see edit history)

[37Special]

It runs again! After pulling out some hair d testing everything the culprit was the terminal insulator post the negative coil wire goes to that then goes to the points.  That plastic around it had rotted so I bypassed it with a wire.  So I think two things happened, my pertronix went bad after only 2 years and then when I put the old ignition back in that terminal post was also bad.  Thank you very much for everyone's help! Anyone know where I can get a new one of those posts? I found some from a tractor store for a Delco Remy distributor. Looks similar to mine.