Help With Understanding Ignition Coils... - Allpar Forums for Chrysler, Dodge, Jeep, Plymouth, and more

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#1 Guest_73_duster_*

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Posted 13 December 2008 - 06:24 PM

If you were a registered user, you would not be seeing this!

I am installing an MS ignition and coil for my car due to fouling plugs and cold winters. I have chosen the Mallory HyFire ignition box (digital) with rev limiter, the specs show a very low current draw but a higher output then leading companies, and is cheaper. If anyone has anything bad to say about this box, then feel free to say. I now have to select an ignition coil and I'm a little confused about how to choose one right for my vehicle.

The car is a 73 duster with a 360ci., street/strip engine, mild cam, 9.3:1 CR. blah blah blah. And I'd like to choose a coil that works well until about 6000rpm. The problem is that companies i've looked at don't give the power range of there coils. And on top of that, articles about choosing the right coil that I have read don't make sense to me at all.

So basically, in a coil, what do you really need to look at to get good spark and a power range you need? If anyone has the answers, I'm curious about a few things.
1. Whats the difference in faster turns ratio compared to slower turns ratio?
2. How does maximum voltage affect the engine performance? does it affect the power band? or altogether, is more better?
3. How does the peak current affect the performance?
4. How does the spark duration affect performance?
5. What is inductance? And how does it affect performance?
6. How can I easily compare different coils when the resistances are different?
7. And lastly, what coil specs would be in a ballpark of what I need for my engine?

Thanks for all who answer, and I think this post could also benefit others, because I've heard that there is a lot of misunderstanding when it comes to coils.

P.S. Dana44, thanks for the answer about my carb. question a while back. When I checked back on the post, I figured it wasn't worth reviving it, so I never responded.

This post has been edited by 73_duster: 13 December 2008 - 06:26 PM

#2 MOPEkid

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Posted 13 December 2008 - 07:23 PM

I have the Mallory HyFire 6A box on my '70 Duster 318 along with a Mallory canister-type coil and NGK V-power plugs and they all worked great for the couple months before my engine went kaput. I don't think selecting a coil is that big a deal; normally you just go with the coil that the company recommends with its ignition system, which in this case is the Promaster or stock-type canister.

This post has been edited by MOPEkid: 13 December 2008 - 07:23 PM

#3 Guest_73_duster_*

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Posted 13 December 2008 - 09:44 PM

MOPEkid, on Dec 13 2008, 07:23 PM, said:

I've read in a couple of articles that choosing the wrong coil can actually make performance take a backstep. For example. The MSD Blaster 2 coil gets its power anywhere from around 6000rpm-10000rpm. So even though the Blaster is recommended by MSD with some of there boxes, it won't help a whole lot for the average car.

#4 dana44

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Posted 16 December 2008 - 05:24 PM

73, lots of questions and I don't have the answers along with very few inputs, either. I usually use things like Mallory Unilites (for their compactness and ease in wiring, along with good performance), and I have had good luck with Mallory coils, and Accel (Super Coils). Stock coils for stock applications is usually OK, but as far as the power boxes go, never had too much of a need for them. I did have a small block Chevy with a stock coil that was difficult to start in cold weather, but I atributed its starting problems more to bad wires and running a little rich. Once I raised the compression I never had the problem, an improper gap on the plugs (both too wide and too narrow have problems when trying to start the cold engine), and later I found out that the Accel sparkplugs lasted longer, didn't burn out so fast, also helped.

As far as the carb goes, you are welcome.

#5 bguy

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Posted 16 December 2008 - 07:15 PM

If nothing else, make sure you get the current draw right. Wouldn't want to burn your wiring harness.

#6 schelled

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Posted 17 December 2008 - 12:48 PM

Although coils are rated for various voltage, the actual firing voltage only goes as high as it needs to to jump the gap....replacing a stock coil with a high voltage one won't raise the firing voltage....variables like compression ratio, type of fuel and other factors determine how hard it is for the spark to jump across the gap....fouling plugs might be as a result of poor coil performance but unless you have a lot of mods done to your engine you probably just need to replace the coil with a stock new one

#7 AC TC

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Posted 18 December 2008 - 04:39 PM

Mother sells a kit with distributor and ecu which i found to be good.
Remember you only need one good spark at the right moment.
I would try to solve fouling in an "rather mild and maybe streetdriven" engine
by changeing to a MS ign.
Find out why its fouling plugs.
Vac connected?
Not overly rich..my 225 /6 runs very good at 0.1% co! Actually passed the test for newer cat con cars.
Not sucking oil?
etc

#8 Guest_73_duster_*

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Posted 21 December 2008 - 06:13 PM

schelled, on Dec 17 2008, 12:48 PM, said:

I found this very helpful if it is in fact true. And I'm also upgrading to an MS box for performance (not just fouling or cold starts). And I found a Summit knock-off coil for $50 that sounds decent.
Thanks for the answers.

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