Ignition Coil differences

ecohen2

ecohen2

True Classic
This might be a silly question, but I keep on getting different answers from different people.

What is the difference between an ignition coil for points / condenser versus the electronic ignition in our cars? Will I damage the car by using the wrong one or was this just a part number difference?

Thanks,
Ed
 
Which setup do you have? I would not use a coil intended for points / condenser setup with a HEI / Electronic Ignition system. The basic function is of course the same regardless, but I would not assume the coil specification is cross-compatible.
 
I completely understand the function and purpose of a coil. What I don't understand is why they would have a different specification. The rate of firing is exactly the same between both setups and the voltage going to the plug should be the same. So what would the difference be and why?

I currently have the stock 86 Bertone electronic ignition setup. I am considering switching over to a solid state coil which I had done in my Scorpion and loved it. A couple of places sell these units, but it isn't clear to me if all electronic ignition coils are the same. Henk has a nice one that was designed for his points replacement setup so does that mean it works with the Bertone electronic ignition as well?


Ed
 
I suspect our new friend from Bangalore is a purveyor of a certain brand of canned spiced ham :cool:

I wish we got the "stock electronic ignition" this side of the pond! Points ignition coils generally have a secondary resistance of 3 or more ohms. Electronic ignition coils tend to be 1.5 ohms or less. That's the main difference. I once used a "dry" coil with an electronic coil driver but it failed because I used one with too low a resistance. It ran fine for a couple of thousand miles but eventually melted one of the tiny connecting wires inside the igniter module. The moral is - get a coil with secondary resistance matching your system spec.
 
ecohen2 said:
I completely understand the function and purpose of a coil. What I don't understand is why they would have a different specification. The rate of firing is exactly the same between both setups and the voltage going to the plug should be the same. So what would the difference be and why?

I currently have the stock 86 Bertone electronic ignition setup. I am considering switching over to a solid state coil which I had done in my Scorpion and loved it. A couple of places sell these units, but it isn't clear to me if all electronic ignition coils are the same. Henk has a nice one that was designed for his points replacement setup so does that mean it works with the Bertone electronic ignition as well?


Ed
Click to expand...

Hi Ed,

Your car is injected, right? If so, the ignition module on the right side of the car controls the spark. So the coil is designed/optimized to work with that module. Although, it's not to say that another option won't work.

So in essence, you have a "solid state coil" - except that the solid state portion is located outside of the coil. I'd keep it as is - no reason to change it. It works well enough in my opinion. Yes, the module does draw more current - but I have enough miles/kms under my belt to attest to the reliability of the system. I haven't changed anything!
 
Actually a solid state coil is quite a bit different than a oil filled coil. I agree that I have electronic ignition, but the coil that creates the voltage for the spark plug is full of oil and eventually loses its capability to deliver a strong spark when it is hot or at higher RPMs. Usually people just wait until they die, but I prefer not to get stuck somewhere with a 30 year old coil.. Switching to a solid state coil reduces the power draw and delivers a far more consistent spark at high RPMs even when they are hot..

Time to write some manufactures and find out the difference.... Ill post the results when I get them...

Ed
 

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Hi Ed,

I might be wrong - but to me that's just a regular coil that you have pictured. Meaning, it's an air cooled core and a winding. An oil filled coil is still a copper wire around a core. You remove the "power" to the coil and the collapsing field generates the nice spark on the secondary.

To me - solid state means "transistors". My UnoTurbo coil is solid state, as it has an integrated electronics. My lawnmower has a solid state coil.

after 35 years of extreme temperature cycling (OK, mostly warm days to VERY hot engine bay) my coil has survived (knock on wood!!). I'm sure yours is in far better condition than mine.


So not all coils are the same - meaning, the primary windings may not be the same (part of your original question). Perhaps it's by design, limitations to the operating temp of the insulation on the copper, etc - and a nice balance so that they won't blow up points for points type, and won't destroy upstream electronics for our Bosch system.

Good question though!!
 
Hi Ed , while am not familiar with the electronic ignition in US models Ive had a similar experience upon converting standard points system to an electronic setup. I retained the original coil and it ran great for around 5000 miles but then problems arose, misfire under heavy load , stalling without restart for an hour sometimes and some good old backfire to scare the oldies. These were all down to the coil when it was overheating , mainly due to the fact of electronic ignition generating a higher voltage spark than standard set up . Be a boy scout "be prepared" get a relevant coil , I uprated to a sports coil, no issues for 20k , surely the cost is worth not being redfaced at side of road, fix it once fix it good.

In my situation this would have certainly caused damage if I didn't replace it when I did,

Hope it helps make up your mind .
 
I am just going for the Vicks Auto red-coil replacement... I reached out to a couple of vendors and this appears to be a topic that nobody actually knows the answer... There are a couple of really good websites that explain the difference between single oil filled coil, coil packs and on plug coils, but nothing that describes the difference between what is needed for points vs electronic...
 
For points distributors:
Bosch K - 0 221 119 027 or 9 220 081 083 = 17500kV
This is one of many "Bosch Blue" coils. Don't go by color alone, get the right p/n.

For electronic:
Bosch KW 0 221 119 030 1.4 - 1.8 Ohm 26500kV
This is called "Super Red" and is used on just about every european high energy ignition system.

The difference between the two, per your question, is the amount of resistance and voltage. An electronic ignition coil will fry the points on a breaker system; a breaker system coil will not deliver enough energy for an electronic system to function properly.
 
Ed , Brad has just clarified what you need with the technical stats too of the coils required .It was a lucas coil I used on marelli based system , lucas normally gets bad press but some items do actually do the business. Not familiar with your motor factors but I still get a kick out of calling them up and asking for a set of points , then the silence , then "sorry what was that you've asked for " makes my day .

Hope you get sorted, they many a wise man on here to keep you right !
 
Ok Ed, I'll bite. To generate a spark, the coil's primary winding current is interrupted by the points, or by an electronic switch. This causes a collapse in the magnetic field which in turn generates a high voltage in the secondary winding. In order to perform well at high revs, the coil can't have too high a primary resistance because the current takes a finite length of time to build back up after it's interrupted to be enough to generate a good spark the next time it's interrupted. This is known as "dwell" time. Points have a fixed dwell angle, controlled by the points gap that you set. This means that at low revs the dwell time is long and at high revs the dwell time is short. Thus for points the dwell angle is a compromise between adequate sparks at high revs, and overheating the coil at low revs. Along with this, a 12V points type coil needs a resistance of around 3 ohms to give good performance without overheating. The big advantage of electronic ignition is that it can provide the correct dwell time to suit the revs, thus not overheating the coil at low revs and still giving a good spark at high revs. Therefore electronic type coils can have much lower resistance, typically 1 to 1.5 ohms, giving a good high peak current and a fat spark at all revs.

The upshot is if you use a points type coil with electronic ignition you are not getting the best out of the system. If you use an electronic type coil with points you will overheat it and burn the points. If you use a too low resistance coil for your electronic system, you will overstress it and possibly release its smoke.

Does that help?
 
Yesterday I finally upgraded my 30 year old coil with a red coil from Vicks. Although my original coil worked, the car run much smoother with the new coil, especially when it is hot.

I have to say thank you to Vicks Auto... The first coil that was shipped out to me was damaged and they sent another one out ASAP. It is great to have decent vendors support our cars...
 
I wanted to add one more note to this.. I am not 100% sure about this because I didn't do any readings before I swapped out my coil. If I am not mistaken, my catalytic converter isn't getting outrageously hot now, it seems just normal exhaust hot.

My guess is that if you have a weak coil the engine dumping out enough excess fuel to really heat up the catalytic converter.. Any thoughts?
 
I suppose that is certainly possible. Cat will get hot if it receives unburned fuel, or not completely combusted fuel, so logically if the coil was producing a weak spark you were experiencing incomplete combustion. Now that you have a strong spark and you are experiencing improved performance it makes sense to me.
You may also experience improved fuel economy...
Engine efficiency is all about being finely tuned, getting it right makes a huge differnence.
 
Isn't the purpose of the O2 sensor to adjust mixture so that you would not be getting a fuel dump? Ii could see this with a carb motor but not so much with an injected motor.
 
carl said:
Isn't the purpose of the O2 sensor to adjust mixture so that you would not be getting a fuel dump? Ii could see this with a carb motor but not so much with an injected motor.
Click to expand...


You are correct! However, I suspect that the range is very limited. I believe this because unlike modern day Bosch fuel injection, ours have a switch to compensate for higher altitude.. If the system was able to adapt to "rich" conditions, they wouldn't need that switch on the ECU...

Ed
 
If the ignition mis-fire is significant enough, the raw air-fuel mixture will toast the cat converter in short time. The cat will not be hot, it will be molten internally and would have melted. More likely given the age and design of cats from that time, it is way past due for a modern replacement.

There is little wrong with the stock Bosch electronic ignition system. It is also integrated into the Bosch L-Jetronic injection system. Going to a higher output coil is not likely going to make much of any difference unless there is a problem with the coil. If there is known mis-fire, better check the spark plugs, spark plug wires and connectors, dizzy cap and specially the rotor. How old are these parts and what is their condition, mileage means just about zero as condition is what's relevant. Also, make absolute sure all the coil and EI system connections and wires are absolutely solid with proven good connections. One flaky connection (the push on spades used often loose their tension resulting in poor connections) can cause all sorts of grief.

Bernice
 
carl said:
Isn't the purpose of the O2 sensor to adjust mixture so that you would not be getting a fuel dump? Ii could see this with a carb motor but not so much with an injected motor.
Click to expand...

The range of l jetronic capabilities relative to the o2 sensor reading is quite narrow and based on normal functioning condition of the engine; a fuel dump is not normal. It has no compensation for engine misfires other than to "keep trying to run," which may ultimately result in a burnt cat. Rowrrrr
 
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