[dlloyd]

I have a 1965 GTO 421 Tripower. I was driving along and all of a sudden the motor shut off like it had been switched off.
The starter was working but motor not even trying to crank. I checked alternator wiring as well as voltage regulator. Wires looked fine. Wires on coil look fine.
I twisted wires on coil and then tried cranking the car.
It cranked. I was about a mile from home and the car cut out 2 more times before I got home with the last time as I was about to drive into the garage.
It was getting harder and harder to get it to crank each time it quit.
Any ideas? Do I need to replace the coil or something else? How do I test these devices to see which one is bad?

[Joe's Garage]

If it does, it sounds like the coil could be going bad.

After a long life, they some times leak out the oil and don't cool as well. When they get hot, they just stop making spark.

Once they cool back down, spark comes back.

And it sounds like it 'cranks' just fine, if the starter was engaging and spinning the motor over. It just wouldn't 'fire' (or start).

You can test the coil be measuring the resistance and verify that it is bad.

If it has ANY type of points-replacing electronic conversion inside the distributor - check there, too. Heat is a killer for those modules.

And don't be surprised if it isn't an electrical issue.

Fuel pumps and needles and seats don't like the new fuels.....

Good luck!

[steve25]

I have had this issue a few times with a original points type dizzy.

If it’s caused by what the issue was with mine , its due to the wire that runs from points under the breaker plate loosing most if not all of its insulation and shorting out all the time, or intermittently like what might be your case when the vacuum advance pulls the points plate back and forth.

If you have a voltmeter you can unhook the wire a the points and yank it around while looking at the meter set for continuity and hooked up between the points wire and ground,

[dlloyd]

Originally Posted by steve25

I have had this issue a few times with a original points type dizzy.

If it’s caused by what the issue was with mine , its due to the wire that runs from points under the breaker plate loosing most if not all of its insulation and shorting out all the time, or intermittently like what might be your case when the vacuum advance pulls the points plate back and forth.

If you have a voltmeter you can unhook the wire a the points and yank it around while looking at the meter set for continuity and hooked up between the points wire and ground,

Thanks for the reply Steve. I don’t have points. I have a MSD electronic distributor. There is no vacuum advanced used. I will say when it cranked it still ran fine and had power.

[dlloyd]

Originally Posted by Joe's Garage

If it does, it sounds like the coil could be going bad.

After a long life, they some times leak out the oil and don't cool as well. When they get hot, they just stop making spark.

Once they cool back down, spark comes back.

And it sounds like it 'cranks' just fine, if the starter was engaging and spinning the motor over. It just wouldn't 'fire' (or start).

You can test the coil be measuring the resistance and verify that it is bad.

If it has ANY type of points-replacing electronic conversion inside the distributor - check there, too. Heat is a killer for those modules.

And don't be surprised if it isn't an electrical issue.

Fuel pumps and needles and seats don't like the new fuels.....

Good luck!

Thanks for the reply Joe. I feel dumb for asking but can you explain how to check the resistance. What would be a good reading and bad reading?

[Joe's Garage]

Coils are oil-filled - you can shake them and hear the oil inside.

Check for ANY leakage or oiliness, especially around the coil wire to distributor attachment. If it leaks, it's bad.

Testing with an ohm meter goes like this:

Primary resistance test:
Set your meter on ohms. Touch black lead to (-) terminal and red lead to (+) terminal. Reading should be between 1.0 and 1.7 ohms.

Secondary resistance test:
Set your meter on Kilo Ohms. Touch the black lead to the center coil wire terminal. Touch the red lead to the (+) terminal. Reading should be between 7.5k and 14.5k ohms.

Here is a video on Youtube: https://www.youtube.com/watch?v=Rk1q3LHHQow

And here is a diagram showing the test specs you're looking for on a stock coil:
https://contentinfo.autozone.com/zne...coil_specs.pdf

If it's an aftermarket coil, you'd want to check what the specs are from the manufacturer, but you'd test the coil the same way.

Examples:
Accel Super Coil (the great big yellow one) #140001
Primary resistance 0.7 Ohms
Secondary resistance 11.8 k Ohms

Accel normal size coil (chrome and yellow)#8140 or 8140C
Primary resist 0.7 Ohms
Secondary 11.8 k Ohms

MSD Blaster 2 Ignition Coil #8202
0.7 OHMs Primary Resistance
4.5 K OHMs Secondary Resistance

My guess would be on the module inside the distributor is getting too hot, but I'm not sure what the test procedure is for the MSD modules

MSD is owned by Holley now. Customer Service is 866-464-6553
Here's a link to a 150+ page PDF for troubleshooting.
https://documents.holley.com/techlib..._wdtn_2014.pdf

Good luck!

[steve25]

You can test a coil very easy with just a short lenght of wire and one of your spark plugs and spark plug wires.

A coil throws a spark when the wire on the negative terminal of the coil makes and breaks its connection to ground , either by means of points or a electronic module as in your case.

If you unhook the module wire going to you negative coil terminal and then turn your ignition switch to run, then your coil should get power to the coils positive terminal.

If you then make and break a connection from the coils negative terminal to ground, then if the coil is good and you have a plug hooked up to the coil andthe plug is also grounded you will see a spark across the plug gap.

This would prove that the coil is good when cold, but the other half of the question to be nailed down is the coil still good when hot from under hood temperatures.

When I was not running aHEI type Dizzy I always had spare known good stock coil in the trunck!

[dmac]

Originally Posted by steve25

I have had this issue a few times with a original points type dizzy.

If it’s caused by what the issue was with mine , its due to the wire that runs from points under the breaker plate loosing most if not all of its insulation and shorting out all the time, or intermittently like what might be your case when the vacuum advance pulls the points plate back and forth.

If you have a voltmeter you can unhook the wire a the points and yank it around while looking at the meter set for continuity and hooked up between the points wire and ground,

That exact issue happened to me in a brand new car with electronic ignition in an 83(?) chevy I had bought specifically to make a cross country trip in. It happened 3 times at highways speeds.

First time it restarted after maybe half hour about 6 hours into what was to be 24 hours of nonstop driving.

Second time I had to have it towed about 25 miles to the nearest dealer. whose mechanic replaced the module after being kind enough to come back to the shop at about 7 pm on Friday night. and must have jiggled the wire enough while replacing the module to make the connection. That added maybe 2-3 hours between waiting for the tow and the repair.

Third time was in the middle of Arizona in the middle of the night about 7 hours later, and had to have it towed about 70 miles in the wrong direction to the nearest dealer. Had to wait over an hour for the tow. I had to spend 2 nights in a cheap motel in Kingman, Arizona because it was now the weekend after the earlier delays. Monday morning, the shop called me at the motel, told me they had replace the wire, and car ran fine for the next 4 years.

Intermittent electrical issues are the worst, and now, for the last almost 40 years, I hate Arizona

[steve25]

Boy, that was hell for you!
Makes me feel lucky I was only stuck for 2 hours as I figured out what was wrong, but had to wait a while just to let motor cool down enough to hold onto the Dizzy and get it out of the motor.

[dlloyd]

Originally Posted by Joe's Garage

Coils are oil-filled - you can shake them and hear the oil inside.

Check for ANY leakage or oiliness, especially around the coil wire to distributor attachment. If it leaks, it's bad.

Testing with an ohm meter goes like this:

Primary resistance test:
Set your meter on ohms. Touch black lead to (-) terminal and red lead to (+) terminal. Reading should be between 1.0 and 1.7 ohms.

Secondary resistance test:
Set your meter on Kilo Ohms. Touch the black lead to the center coil wire terminal. Touch the red lead to the (+) terminal. Reading should be between 7.5k and 14.5k ohms.

Here is a video on Youtube: https://www.youtube.com/watch?v=Rk1q3LHHQow

And here is a diagram showing the test specs you're looking for on a stock coil:
https://contentinfo.autozone.com/zne...coil_specs.pdf

If it's an aftermarket coil, you'd want to check what the specs are from the manufacturer, but you'd test the coil the same way.

Examples:
Accel Super Coil (the great big yellow one) #140001
Primary resistance 0.7 Ohms
Secondary resistance 11.8 k Ohms

Accel normal size coil (chrome and yellow)#8140 or 8140C
Primary resist 0.7 Ohms
Secondary 11.8 k Ohms

MSD Blaster 2 Ignition Coil #8202
0.7 OHMs Primary Resistance
4.5 K OHMs Secondary Resistance

My guess would be on the module inside the distributor is getting too hot, but I'm not sure what the test procedure is for the MSD modules

MSD is owned by Holley now. Customer Service is 866-464-6553
Here's a link to a 150+ page PDF for troubleshooting.
https://documents.holley.com/techlib..._wdtn_2014.pdf

Good luck!

This is awesome! I appreciate this. I will be testing the coil this weekend. I will let you know what comes out of this.

[dlloyd]

Originally Posted by steve25

You can test a coil very easy with just a short lenght of wire and one of your spark plugs and spark plug wires.

A coil throws a spark when the wire on the negative terminal of the coil makes and breaks its connection to ground , either by means of points or a electronic module as in your case.

If you unhook the module wire going to you negative coil terminal and then turn your ignition switch to run, then your coil should get power to the coils positive terminal.

If you then make and break a connection from the coils negative terminal to ground, then if the coil is good and you have a plug hooked up to the coil andthe plug is also grounded you will see a spark across the plug gap.

This would prove that the coil is good when cold, but the other half of the question to be nailed down is the coil still good when hot from under hood temperatures.

When I was not running aHEI type Dizzy I always had spare known good stock coil in the trunck!

Thanks Steve for the info.

[dlloyd]

I replaced the coil and that made no difference.
I then replaced the MSD ready to run distributor and my problem is solved. My car even seams to run and idle better than it has in a long time. This may have fixed my idle issues I have been working on for last year. I am not sure if the distributor can slowly go out like that or not but it sure seems to have fixed more than the shutting down issue I had.
I do have a question for you guys. Can I replace the module in the old distributor and have for a spare?

[abefromen]

Originally Posted by dlloyd

. Can I replace the module in the old distributor and have for a spare?

If I am not mistaken I think it has to go back to MSD to have it changed, some kind of involved process.

Not the first time I have heard of someone having issues with those MSD Ready To Fail distributors.