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Old 10-14-2011, 06:57 PM   #1
ldj1002
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Default coil questions

As I understand there is only 2 ways to set a buzz coil correctly, a hcct or strobospark. I have read of some other options than using buzz coils but not this. Why couldn't you use regular automotive coils? Looks like you could build a nice little box for them and have the timer fire them just like it does a buzz coil.
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Old 10-14-2011, 08:37 PM   #2
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Default Re: coil questions

You need to HCCT or Strobo because they are the only way to actually tell if the coil is firing once or if it is having a double spark, which means the coil fires before and after when it is supposed to, instead of once in the exact sweet spot.
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Old 10-15-2011, 10:02 PM   #3
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Default Re: coil questions

In thinking about this I can't really see any reason, beyond needing 6 vt. coils and some fancy wiring, that modern coils would not work. Plus on the coil to power, negative on the coil to the proper timer wire and of course the high tension output to the plug wire. Depending on the size of the coils you might even fit the whole concoction into the coil box for an original look. The only possible problem that comes to mind is the AC current from the mag and the fact that it varies so much with engine speed. I don't know if modern coils will work on AC. Of course if your battery powering the thing that point is moot as they will work on DC current. I might be mistaken but I think the Tru-Fire unit that is sold to replace the coil boxes works something like what you propose. A cheap check would involve a coil and an AC power source like the accessory terminals on a toy train transformer just to see if AC would work.
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Old 10-16-2011, 12:17 AM   #4
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Default Re: coil questions

Do the modern automotive coils need a trembler box? they might if they did not produce alot of spark on A/C unless you set it so that each time the timer lost contact with that coil that the piston was at the part of the firing stroke the timer rod was aiming for
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Old 10-16-2011, 08:16 AM   #5
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Default Re: coil questions

Tell me again, how are you going to time the firing of the coils? Without the original coils or a distributor, you can't get the intercylinder timing precise enough. Why not just fix it the right way and worry about something else?
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Old 10-16-2011, 03:22 PM   #6
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Default Re: coil questions

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The coils would fire when the timer roller grounds them just as it does in a regular T coil setup. You understand you do need 4 modern coils. The positives could be hooked together. The grounds come from the timer wires and each coil would have it's high tension terminal going to each individual spark plug terminal. Timing would be achieved in the normal manner by moving the spark lever and therefore the timer. As I said before, aside from a possible problem of running the modern coils on AC there's no reason this would not work and is being done with the Tu-Fire system. The Tru-Fire ads do say 6 or 12 volt systems so it may be battery powered.
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Old 10-16-2011, 03:40 PM   #7
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Default Re: coil questions

To Dumb: a modern coil does not need a trembeler box or any thing else besides DC voltage, (6 or 12) to the proper terminals. Usually the 2 screw or blade connections on either side of the high tension output terminal. Hook up power as described and it fires. Continously. Until the circuit is broken. Sound too good to be true, doesn't it? Well it isn't. Why wasn't it done "back in the day" and why hasn't it caught on today? Damned if I know. I proposed this on the MTFCA site years ago and promptly got my rear end handed to me. No body said it wouldn't work but the keep it original guys ran me out of town. The only reason I haven't tried it myself is the lack of parts. I haven't found a coil box at a decent price to experiment with. If I ever do you can be sure I'll invest in 4 modern 6 vt. coils ( with built in resistors) and give it a shot.
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Old 10-16-2011, 05:52 PM   #8
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Default Re: coil questions

Charlie, from the above statement, you obviously don't understand how a modern coil works. "Hook up power as described and it fires. Continously. Until the circuit is broken." Is totally incorrect. Borrow some parts and try this one thing first.
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Old 10-16-2011, 07:03 PM   #9
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Default Re: coil questions

The modern coil fires only once at the precice time that the circuit is opened. It will not fire continuously like a buzz coil. Left connected continuously most modern coils will overheat & burn out.

A modern coil relys on DC current to operate.

The roller arrangement in a T timer probably does not have a clean enough break in the circuit to fire a modern coil with good results.

The condenser is necessary to cause the spark to be produced & it keeps th points from burning as well.

The True-Fire system does indeed use very modern coils but it is triggered by a modern magnetic pick up that replaces the timer.

All in all it is hard to beat the original system that works well when set up any where close to correctly & can be convinced to get you home in the event of trouble with the extra coil that usually rattles around under the seat & a few wooden matches stuffed in just the right spots to make the contacts work.
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Old 10-16-2011, 08:03 PM   #10
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Default Re: coil questions

You are correct. It won't fire continously. Fingers ahead of brains. I agree, (and have in my '23) an original coil setup. HCCT set coils that work normally. Been told they'll last for years. We'll see I guess. Still, today, a reasonably priced and hidden alternative requireing no maintenence is what I'll go for if possible.
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Old 10-17-2011, 07:17 AM   #11
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Default Re: coil questions

IDJ, I believe you would be time and money ahead to use newly rebuilt model T coils . Ron Paterson has very good ones reasonable.

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Old 10-17-2011, 08:31 AM   #12
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Default Re: coil questions

Thanks all. I am wanting to do this just to see if it works. I am going to try in a day or so by removing just 1 buzz coil and replacing it a modern coil in its place. A buzz coil sparks when the timer makes contact. A modern coil will fire when the timer brakes contact. So therefore that modern coil will be firing a little later than a buzz coil in it's place.
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Old 10-17-2011, 12:14 PM   #13
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Default Re: coil questions

Quote:
Originally Posted by Farmallcub49 View Post
You need to HCCT or Strobo because they are the only way to actually tell if the coil is firing once or if it is having a double spark, which means the coil fires before and after when it is supposed to, instead of once in the exact sweet spot.
If I understand correctly, the coils fire multiple times on each power stroke, for as long as the commutator is grounding that coil. And if I recall, each coil is grounded for something like 15 degrees of camshaft rotation. So what do you mean by "double spark", given the fact that there are many more than two sparks coming out of the coil each time?

Last edited by Will N; 10-17-2011 at 02:18 PM.
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Old 10-17-2011, 12:32 PM   #14
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Default Re: coil questions

Think double spark is where the magneto puts out one pulse but the coil has 2 distinct sparks that are not quite as powerful as a single spark from a single pulse
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Old 10-17-2011, 05:43 PM   #15
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Default Re: coil questions

Will, your understanding is incorrect. The Model T coil needs 1.3 amps to fire if adjusted correctly. It is only possible to fire usefully once during the combustion cycle. Any further sparks would be way after TDC and not of any use to combustion. The same will happen in LDJs test, the modern coil will be so late so as not to have any use to combustion other than maybe a backfire through the muffler. Double sparking occurs when the coil fires before the 1.3 amp buildup is achieved and the coil is able to fire multiple times. This results in a less than satisfactory spark and subsequent sparks are wasted and a weak cylinder is felt. There is documentation available if you would like to read it that explains in great detail how it works. Let me know if you want to see it.
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Old 10-18-2011, 07:24 AM   #16
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Default Re: coil questions

Doug, Thanks for your explanation, and yes, I would love to see the documentation!
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Old 10-18-2011, 11:58 AM   #17
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Default Re: coil questions

These are listed in order of importance in my opinion. A lot of reading, but it will give you a good understanding of how they work. Hope this helps.

http://www.funprojects.com/pdf/Model...0Artiticle.pdf

http://www.funprojects.com/pdf/More%...k%20Timing.pdf

http://www.funprojects.com/pdf/The%2...20Part%201.pdf

http://www.funprojects.com/pdf/The%2...20Part%202.pdf

http://www.funprojects.com/pdf/The%2...20Part%203.pdf

http://www.funprojects.com/pdf/AccurateSparkTiming.pdf
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Old 10-20-2011, 10:46 AM   #18
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Default Re: coil questions

The double spark that is being talked about is caused by the vibrator spring on the underside of the upper point bridge not being adjusted correctly.
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Old 10-21-2011, 09:01 AM   #19
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Default Re: coil questions

Quote:
Originally Posted by Doug Money View Post
Will, your understanding is incorrect. The Model T coil needs 1.3 amps to fire if adjusted correctly. It is only possible to fire usefully once during the combustion cycle. Any further sparks would be way after TDC and not of any use to combustion. The same will happen in LDJs test, the modern coil will be so late so as not to have any use to combustion other than maybe a backfire through the muffler. Double sparking occurs when the coil fires before the 1.3 amp buildup is achieved and the coil is able to fire multiple times. This results in a less than satisfactory spark and subsequent sparks are wasted and a weak cylinder is felt. There is documentation available if you would like to read it that explains in great detail how it works. Let me know if you want to see it.
Doug ,

Some very good info here for sure. Even if the T coil fires multiple times only one will be the working one. Had a chance to check a T Coil with 6 and 12 volts this morning using a current probe and observe the firing current build up and release . The first firing of the coil would be the spark timing of the T engine and the others would just be wasted with no help to power etc.
I do however find it almost impossible to adjust the coil to have only a single spark however.
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Old 10-21-2011, 09:07 AM   #20
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Default Re: coil questions

Scope waveform of T coil using fluke current probe. Not unlike any coil action we have seen or see , the multiple spark is the only major difference. The coil build up and turn on /off is basically the same as its always been....There was a 1 amp difference in current from six to 12 volts.
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