Electronic ignition - Ballast resistor

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Calovera
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Electronic ignition - Ballast resistor

Post by Calovera » Mon Nov 04, 2019 7:11 pm

So, one of my to-do jobs is to get an electronic ignition module stuck in the car, just for the sake of reliability. I will be keeping the points in the boot, just in case, knowing my luck.

Once I've figured out what module to get, I've been reading and slightly confused about the ballast resistance. It's an old-looking coil, so I assume it's the 6v. I understand that the electronic module does away with the resistance, so I'll need a new coil. Is it just as simple as swapping out the old coil for new 12v one, rewiring then timing? Or will I have to locate and get rid of the ballast resistor wiring, which I assume is in the loom somewhere?

Bug
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Re: Electronic ignition - Ballast resistor

Post by Bug » Mon Nov 04, 2019 8:44 pm

I believe the coil is more likely to be 9v?
Whatever, it is designed to work with the reduced voltage supplied to it by the ballast resistor.
When you turn the key to start it, the ballast resistor is bypassed, through the starter circuit somehow (memory is a bit hazy), to give a big fat 12v to the coil for a better spark. When you let go of the key it drops back to using the ballast resistor.
The resistor is a fat grey wire hidden in the loom that comes across the bulkhead at the back of the engine bay.
What I did was to find the start of that wire, where it is spliced into the standard thickness of wire (about 4 inches along from the fuse box, if memory serves me right). The drop in voltage is basically achieved by making the 12v fight its way through that thick wire to the coil.
I simply spliced a standard thickness length of wire into the loom just before the resistor and ran that to the coil.
I then disconnected and tied back the existing feed connector from the coil and attached the new one in it's place.
By doing it this way it meant I could fit the old coil and the points back and simply swap the connectors around to use the ballasted feed.

Others may have different methods.

Incidentally, I used the Aldon Ignitor system, paired with the unballasted (12v) Flamethrower coil.

stevemarl
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Re: Electronic ignition - Ballast resistor

Post by stevemarl » Tue Nov 05, 2019 10:49 am

:agree: What he said.

STEVEW
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Re: Electronic ignition - Ballast resistor

Post by STEVEW » Thu Nov 07, 2019 7:00 pm

Hello Calovero

If you choose to use the Powerspark ignition kit there is information on the Powerspark Ignition – BLOG.

It’s not a case of 12v or 6v coils: the ballast resistor supplies the coil with 6v under normal running conditions, i.e., the ignition switch is in the “run” position.
Upon starting the engine, when the ignition switch is in the “start” position, the ballast resistor is by-passed thus giving 12v to the coil which improves starting. Release the key and the switch springs to “run”: the system again operating through the ballast resistor on 6v.

What is important is the internal primary resistance of the coil. According to Powerspark’s blog this should be about 1.5 Ω, which is measured between the two LT posts. Our coil measured 1.4 Ω, which indicates it's a "ballast" coil.

The other ignition unit I know of, which is reasonably priced is the Akkuspark.

PS. What engine do you have in your Capri?

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Re: Electronic ignition - Ballast resistor

Post by stevemarl » Fri Nov 08, 2019 11:23 am

STEVEW wrote:
Thu Nov 07, 2019 7:00 pm
It’s not a case of 12v or 6v coils:
I understand what you`re saying and the rest is correct, but there ARE 6v and 12v coils. If you use a 6v coil without a ballast the 12v it will have across it will cause it to overheat. Equally a 12v coil running at 6v will not produce it`s rated voltage on the secondary. The ballast doesn`t `give` 6v to the coil, it is a potential divider, 12v across a 1.5ohm ballast resistor in series with a 1.5ohm primary coil = 6v across each. (Don`t forget 1.5ohm can be a mile of thick wire or a foot of very fine wire, they have the same resistance but can`t carry the same current.)

Calovera
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Re: Electronic ignition - Ballast resistor

Post by Calovera » Fri Nov 08, 2019 3:43 pm

I called up tickover and they seemed sure to not worry about the coil.
I'm also running a 1.6l pinto.

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Jasonmarie
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Re: Electronic ignition - Ballast resistor

Post by Jasonmarie » Fri Nov 08, 2019 5:23 pm

Tickover did mine and I kept the original coil .
Ford Capri 2.0 Laser 1987 Mercury Grey ....... :beer:

STEVEW
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Re: Electronic ignition - Ballast resistor

Post by STEVEW » Fri Nov 08, 2019 6:02 pm

Hello Stevemarl

Thanks for the input.
I’m not saying that there aren’t 6v & 12v coils.Perhaps I should have opened my comment in a better way.

Nevertheless, I wanted to bring “Caloverero’s” attention to the resistance across the terminals, which - as I understand - is important.
As he said that his coil is old and assuming his ignition system is working correctly with the Ford Ballast Resistor cable installed then we can assume it is more than likely,
“...of the ballast resistor type and uses a 6v coil.”**
Hence, checking the resistance across the terminals helps here.
I certainly, wouldn’t remove the Ford ballast cable from the loom.
“The coil is designed to run under normal conditions with a 7 volt supply…”**

I mentioned Powerspark because they quote a figure of 1.5 Ω on their blog, which lies within the 0.95 to 1.60 ohms Primary resistance given in the Ford manual.

They also suggest running a separate fused cable to their ignition kit which is live only with the ignition on.
However, we haven’t got that far yet!

**(Ford Manual).

PS. I didn’t say that the ballast gives 6V to the coil. I wrote,
“…the ballast resistor is by-passed thus giving 12v to the coil…”
And, according to the Ford Manual, under starting conditions full battery power is supplied to the coil via the starter solenoid.

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Re: Electronic ignition - Ballast resistor

Post by stevemarl » Fri Nov 08, 2019 8:47 pm

STEVEW wrote:
Fri Nov 08, 2019 6:02 pm
I didn’t say that the ballast gives 6V to the coil. I

I know I`m being a pedant but you DID say
STEVEW wrote:
Thu Nov 07, 2019 7:00 pm
the ballast resistor supplies the coil with 6v
That`s what I took issue with, sorry for any misunderstanding.

Bug
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Re: Electronic ignition - Ballast resistor

Post by Bug » Sat Nov 09, 2019 5:36 pm

I gave a very simple description and solution back at the beginning of this thread.
Whilst all the other input is useful to you, why not take on board actual experience and go with what is proven.
I know I'm not about much on here now, but several people will tell you I have a fair to middling experience with Capris (continually from 1985 until about three years back). A quick search would show that I usually manage to give real world advice based on personal experience.
I had maybe 40 Capris since 1985 and looked after each and every one. I certainly would not do anything as a bodge..............and when I did things wrong I made sure everyone on here heard about it so they learned from my mistakes.
So, anyway, it's up to you of course, but I know what I did worked well and would recommend that route. Saves any worries about resistances, voltages etc.
Let me know how you get on ;)

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