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Anyone running a fuelmiser cc215 coil?


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Hi Jeremy,

                   If you are obsessed with high secondary voltage ability, maybe you should get one of theses !  60,000 Volts.


I'm only joking Mate !  Fit one of those & you'd wouldn't have to worry about bumping roads into town.  You be there in a few minutes, as you Rolla Jeep would be flying !

I note, they make one with a primary winding resistance of 0.32 ohms.  Probably suitable only for Capacitive Discharge Ignition Systems.


Cheers Banjo


Edited by Banjo
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also i should reiterate that I'm not just suspecting a bad coil, it produced a weak spark which i could see as "weak" with my eyes.

this low impendance helped a lot but obviously its just too low. even tho this isnt a petronix, i can definatley agree on the 3 ohms rewuired, as the factory setup would have been a 1.5 ohm coil through a 1.5 ohm ballast resistor.

Further thoughts.

how exactly does the power going through the coik hurt the igniter. It is my (possibly completely wrong) understanding that the coil positive wire simply powers the igniter and the igniter turns on and off the negative circuit from the coil??  or is it the high current going down the negative cicuit being switched on and off by the igniter which causes the problem?

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now hang on

that page u linked for the flam throwr coils shows 3 different type of ig ition systems that they make.

ignitor 2 seems to have the ability to take 12 v coil at 0.45 ohms for 4-5-6 cylinder engines.

that means the minimum requirement is different for that system so the only time we can rely on the rule is when the ignitor has a written recomendation.

how do we know the stock electronic igniter isnt capable of handling it?

perhaps the pertronix gear is is all made at different qualities, cheaper ones can't take the current, more expensive ones can.

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It is my (possibly completely wrong) understanding that the coil positive wire simply powers the igniter and the igniter turns on and off the negative circuit from the coil??  or is it the high current going down the negative cicuit being switched on and off by the igniter which causes the problem?

Both your comments are exactly true.  The power to the ignitor, from the ignition switch, depicted going directly to the Hot Spark module, or via the 1.4 ohm resistor, (if fitted) powers the ignitor control & triggering electronics only.

The "electronic switch" in the ignitor, between coil -ve, ignitor switch, to chassis; only carries the coil primary winding current.   The electronic switch is not a perfect switch.  It drops a very small voltage across it, so generates heat.  It needs to get that heat away, hence why cooling ignitor is important. More current you ask the switch to carry, the hotter it gets. If the ignitor over heats, it will eventually "kill" the ignitor.  That simple !  Hence, why they are so adamant about not fitting coils with lower ohms than specified, as that increases current, & therefore heats the "switch" which it has to dissipate.

Cheers Banjo

Edited by Banjo
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how do we know the stock electronic igniter isnt capable of handling it?

See my Ohms Law calculation earlier in this post.

4K dizzy with interal ignitor can only handle 9A-10A maximum.

Any more, & it will eventually fail, as many 4K users with electronic dizzies will testify.

Cheers Banjo

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right so putting a resistor between coil and igniter is pointless unless ur system voltage is too high , got it.
To be honest i got very confused in your ohms law post, however i think that maybe one of the things that confused me was your calculation listed the ohms as 1.3, and this doesn't match with any igniter setups, as we both now agree it should be 3 ohms for most igniter setups. (whether it be a 3 ohm coil or a 1.5 ohm coil and a 1.5 ohm ballast)
"So if we assume 1.3 ohms as spec'd, & assume a nominal voltage of 12 volts, then R = 12/1.3 = 9.0 amperes."

So i got a reply from fuelmiser....

Good afternoon Jeremy 
At this point in time I can only give you the primary resistance which is 0.8 Ohms 
We are making enquiries with our suppliers for the secondary resistance and once this is available I will email you 

I do have a ballast laying around, i wonder if i should just stick it on with this fuelmiser.......
 hang on just doing up a quick spreadsheet, see next post


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ferk yeah look at this

So the one i want is the 3 ohm, so its only 8kohms.
the 1.5 ohm one is 10.6kohms.

So its only marginally better than the old shitty bosch blue coil

Unfortunately, again no good
and I have just worked out another of my methodology flaws.
I incorrectly stated (in different words) that the factory setup would have better spark because the ballast resistor brings up the resistance. but it does that before the power gets to the coil so its making the coil worse, so that was incorrect of me to say.... the 3 ohm coil is not supplying less power, its converting the power into input on one side of the coil. so the 3 ohms will be giving more input power than a 1.5 ohm coil. not to mention, significantly more than a 1.5 ohm coil which has a 1.5 ohm resistor before it.

what formula would use to work out spark energy, with the following variables

ballast resistor ohms (no resistor or a 1.5 ohm resistor)
system voltage of 13.5
No idea what amps the 13.V is before it gets to the coil
primary ohms
secondary ohms

I'm really sorry, i know too much but not enough. I want to understand this.

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Hi Jeremy,


I'm really sorry, i know too much but not enough. I want to understand this

                  The energy stored by the coil after it reaches saturation, has nothing really to do with amps or volts or resistance.  It has everything to do with the inductance of the coil, which is specified in units called Milli Henries. It's the capacity of the coil to hold a charge of a given size.

Think of the coil as a bucket of water, which you are filling up constantly & then tipping over someones head, say every minute. 

The capacity of the bucket is the equivalent of the energy stored. A small bucket fills quickly, but does hold as much water as a bigger bucket.  However, the larger bucket takes more than a minute to fill, so you never get to tip the bucket over some ones head, at the required rate.

So you need the bigger bucket to store the amount of water needed to wet this person thoroughly. So, how can you get the water into the bucket quicker.

Your stuck with water pressure (12 volts) but you could use a bigger diameter hose (lower resistance). The result is greater flow of water, (more amps)

That's about the simplest analogy I can think of.  The problem here is the time to fill the bucket up.  To continue the analogy, when the bucket fills up, & you keep pouring in water, it overflows.  The bucket has reached full charge (saturation).


Have a read of the above article.  It covers lots of things we have been discussing in every day terms.  It might help you understand the subject a little better.

So this talk of lower resistance & higher currents is all about getting the max. charge into the coil, in the shortest time. Lower the resistance which ups the amps, both result in the charge reaching saturation earlier. If the charge in the coil in not max. when the spark plug is fired, then the duration of the spark inside the combustion chamber will not be sustained long enough to satisfy  complete combustion.

Here is another good read, that has some formulae therein for charge of an ignition coil.  "L" is the inductance.


Hope that helps.

Cheers Banjo

Edited by Banjo
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so i google 4k coil, and i find rollaclub posta which say that the diatrubutor with the internal ignitor like mine is from a toyota 5k.

so i googke 5 k coil and see for sale tridons oil filled coil to suit a liteace. TIC034R , and also the GT40R. (perhaps an indication that i should just get the GT40).

then i google that tridon coil for specs  to confirm but can't find anything, however i was linked back to the tridon book which sais that the TIC034R  is interchangeable with the better transistor type TIC036R.

No specs on that either. But surely its better than jist running blind liie i am now.

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our very own forums wiki sais the gt40 shouldnt be used in this dizzy. and that the electronic ignition "REQUIRES" HEI coil. do we need to edit this?

It also states the HEC716 FROM bosch is the most suitable. this is a 0.4 primary, 7.8kohm secondary. 


So with all the absolutely cotradicting information outvthere, I feel as if I am on my own.

Edited by rebuilder86
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so i just drove in to town to get some gas for the barbie, and had an epiphany,
When i have been testing spark, it has been while cranking engine.
So when i suspected the bosch blue coil as rubbish, that just may be because the 3 ohm winding is weak when cranking.
So I'm going to put it back in, and remove all spark plugs, and turn the engine over by hand and check the spark on that old bosch blue.

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So here is a list of all the coils ive looked into and their approximate rating.
I should only pick from coils that don't have a red figure.

So running a resistor with the GT40 R should be significantly better than just running the GT40 however that doesnt take into account the fact hat the resistor extends the saturation time.
So I'm just going to assume that a GT40R resisted down to 11 volts from 13.5 is taking only a fraction of its saturation speed away and will still be better than a GT40.
At 3.4 ohms, why would the rollaclub wiki article say that the GT40 isnt suitable for electronic ignition?


Hopeful someone finds this info useful in the future.

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