Is a ballast resistor ever used with a Breakerless ignition?

[Lou C]

In all the OMC wiring diagrams I’ve seen I have never seen a separate ballast resistor as was used in automotive systems but they do use a resistance wire in the engine harness for the models with points ignition. You can’t tell from the diagram but it will be referenced in the ignition system section. So you need a factory shop manual to answer this question. Or call the tech guys at CDI electronics in Alabama they can tell you how to determine if one is needed or not.

 

[KM7]

@ Lou: Could be carb related but It seems to be idling better now, just under 800 rpm in the driveway. I'll see what it does in the water. I changed the distributor cap and redid the idle mixture. I'm now at 1 5/8 out both sided. The book says to start at 7/8 out.

Here are 2 videos before and after:

https://youtu.be/IdEym0ynBIs

https://youtu.be/vKqAQJaWFVo

Micro switches work fine. Re OD maintenance; I recently pulled it, replaced the shift cable and adjusted per the book using both tools at the bell crank and up at the cable. I followed your advice and packed that pocked full of OMC grease. Now each time I come out of the water I remove the plug on the starboard side and check for water. None so far !

Plugs - good, Cap - New, rotor - I filed it and have a new one on order, Plug wires - all below 10k ohms per foot that the book says is max. The highest was 13k ohms to cylinder 8. Most around 10k. Do you think I should replace them?

I did pull the fuel line screen right at the carb and there was no crud this time. Before the rebuild there was a lot!!

Watch the videos and tell me what you think.

 

[Lou C]

It seems to idle certainly smoothly enough in the second vid, what happens when you try to get it down to 600? Rough running and or stalling? On my engine the OMC idle spec is 500-600 in gear and in the water. I usually set mine at 600 and then in the water it is slightly lower but not by a lot maybe 50 rpm. Keep in mind though for the shift system ESA it needs to be able to idle at 450 at least momentarily while shifting from in gear to Neutral. What happens to your rpm if you trigger the interrupt lever on that switch? If the base rpm is too high the ESA may not be able to drop the rpm. This would keep it from shifting out of gear...

 

[Lou C]

And if you can’t get it down to 600 on the water hose there may still be dirt restricting the idle circuit. There is a support forum over at Holley.com where you can ask questions.....

 

[KM7]

@ Lou: Could be carb related but It seems to be idling better now, just under 800 rpm in the driveway. I'll see what it does in the water. I changed the distributor cap and redid the idle mixture. I'm now at 1 5/8 out both sided. The book says to start at 7/8 out.

Here are 2 videos before and after:

https://youtu.be/IdEym0ynBIs

https://youtu.be/vKqAQJaWFVo

Micro switches work fine. Re OD maintenance; I recently pulled it, replaced the shift cable and adjusted per the book using both tools at the bell crank and up at the cable. I followed your advice and packed that pocked full of OMC grease. Now each time I come out of the water I remove the plug on the starboard side and check for water. None so far !

Plugs - good, Cap - New, rotor - I filed it and have a new one on order, Plug wires - all below 10k ohms per foot that the book says is max. The highest was 13k ohms to cylinder 8. Most around 10k. Do you think I should replace them?

I did pull the fuel line screen right at the carb and there was no crud this time. Before the rebuild there was a lot!!

Watch the videos and tell me what you think.

 

[froggy1150]

The way the resistor works with the coil is that power is supplied to one end of the windings and the other is grounded. This generates a field. When the circuit is opened the field collapses and has to get rid of all that energy. It's path is to ground thru the second winding.when you charge a coil it only takes milliseconds to get to saturation or what's could be called full. Anything beyond that and the coil will overheat and cook. Without the resistor your voltage and current will be too high. That's why they have a second power feed from the starter while cranking. Because of the voltage drop during this event. The close time on points is greater at idle than it is at max rpm so dwell becomes how you balance. If your points are too tight you overpower the coil at idle. Too big a gap and you loose spark energy at rpm. In its simplest form electronic ignition switches ground with a transistor. All systems are different and so are coils. There are your basic coils, there are coils with internal resistors and also digital coils .you still should get ahold of the mfg of your system and find out specifics but if your coil is hot, not warm it will run but fail soon
fyi

 

[KM7]

froggy Thanks for the advice. My understanding of coils and ballast resistors is this: The primary winding create an electrical field and when the circuit opens the field collapses and sends the energy through the secondary winding. The reason the voltage is higher in the output is because there are many more windings in the secondary field.

A ballast resistor is only needed in a breakerpoint ignition for the reasons you discussed. The dwell controls how long the points stay closed and how much the coil gets charged. The slower the engine is running the more time the points are closed and the more the coil gets charged, At slow speed the charge can become too much, 1) heating up the coil and leading to premature coil failure and 2) causing to large a spark across the points. That's where the ballast resistor comes in. At low rpm the resistance increases in the ballast resistor. That drops the voltage to the coil and 2) prevents it over heating and 2) reducing sparking at the points. At high rpm, the coil does not have enough time to get over charged and the there will be less heating and wear on the points.

A breakerless system does not have points and the coil is designed to take the higher current so a ballast resistor is not needed.

My motor was stock without a ballast resistor so I took it out. I will pay attention to the coil temperature. I wonder if anyone makes a small fan to reduce coil temp??

 

[KM7]

Update: With the ballast resistor removed. (it was not part of the stock design) She is running GREAT!!. Replacing the distributor cap may have also helped.

She idles now around 600 rpm.

That also makes shifting smooth as silk. There is another post from me on that.

So... At least on my boat, the Ballast resistor is not needed. There *may* be a slight possibility that the higher voltage to the coil could make it die sooner, but I doubt it. If I end up with a dead coil I'll post an update.

 

[KM7]

Update: With the ballast resistor removed. (it was not part of the stock design) She is running GREAT!!. Replacing the distributor cap may have also helped.

She idles now around 600 rpm.

That also makes shifting smooth as silk. There is another post from me on that.

So... At least on my boat, the ballast resistor is not needed. There *may* be a slight possibility that the higher voltage to the coil could make it die sooner, but I doubt it. If I end up with a dead coil I'll post an update.

 

[Lou C]

Great follow up!