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Do 'supression' wires have enough resistance?
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MrGoodtunes
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PostPosted: Tue Jun 02, 2015 6:50 pm    Post subject: Do 'supression' wires have enough resistance? Reply with quote

Or, should *everything* from the coil to (and including) spark plugs ALL be resistance type?

My 1600's 009 distributor has a rotor that appears to be resistive. The recommended NGK plugs are BR6HS, where the 'R' means they too are resistive. And I read somewhere that the sparkplug connectors I'm using at the ends of my wires are resistive too. They look like this:

Image may have been reduced in size. Click image to view fullscreen.


I don't use any computerized ignition or anything, don't even have a radio, and my smartphone probably doesn't need the resistance. It seems at some point, there's a chance of having too much resistance. So, go to a higher voltange coil? Engine is running nicely, but any suggestion that might give better performance in terms of acceleration and especially MPGs would be greatly appreciated.

Thanks in advance, MrG
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jhoefer
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PostPosted: Wed Jun 03, 2015 1:35 pm    Post subject: Reply with quote

You really only need one resistance-type item in the chain for EMI suppression. While it might not matter to you, you'll annoy the hell out of everyone you are driving next to without it. I'd probably go with some spiral-wound magnetic suppression plug wires, a resistorless rotor, and non-resistor plugs.
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KTPhil Premium Member
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PostPosted: Wed Jun 03, 2015 6:51 pm    Post subject: Reply with quote

jhoefer wrote:
You really only need one resistance-type item in the chain for EMI suppression. While it might not matter to you, you'll annoy the hell out of everyone you are driving next to without it. I'd probably go with some spiral-wound magnetic suppression plug wires, a resistorless rotor, and non-resistor plugs.


X2. Too much resistance and you will get a weaker spark. The stock bakelite SP connectors had about 5KΩ resistance and the four wires had none. Resistance wires are usually a carbon impregnated fiber that does not last and can develop an open if bent too tightly. When I run out of non-resisor plugs soon, I'll probably be looking for non-resistance connectors to compensate.
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glutamodo Premium Member
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PostPosted: Thu Jun 04, 2015 1:34 am    Post subject: Reply with quote

5K on the plug wire end connectors? I think not. 1K.

Image may have been reduced in size. Click image to view fullscreen.


You might have been thinking of the 04033 rotor, (1234332215) which is 5K.

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61SNRF
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PostPosted: Thu Jun 04, 2015 4:28 am    Post subject: Reply with quote

KTPhil wrote:
Too much resistance and you will get a weaker spark.


Actually, depending on the coil's capacity and state of health more resistance will increase the firing voltage and make the spark stronger or "hotter" Wink

Remember the old anti-foul adapters you put inline in the plug wire?
All they were was an air gap for the spark to jump to increase the firing voltage.

The limits of secondary circuit resistance being too high come from:
1- How much capacity the coil has...
2-Too high and the spark may seek an easier path to ground, or in other words short through the wire to ground causing a misfire.
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Dr OnHolliday
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PostPosted: Thu Jun 04, 2015 12:09 pm    Post subject: Reply with quote

You don't NEED any resistance anywhere in the ignition system - copper components have worked great for over 100 years
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KTPhil Premium Member
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PostPosted: Thu Jun 04, 2015 1:49 pm    Post subject: Reply with quote

61SNRF wrote:
more resistance will increase the firing voltage


I'm trying to figure out how this can be... cold fusion? Wink A given power through a higher resistance must produce a lower voltage. True for AC or DC. Ohm's Law and all that.

Unless it "loads" the coil differently somehow and increases the current? That's where I start mumbling to myself...
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Aussiebug
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PostPosted: Thu Jun 04, 2015 3:55 pm    Post subject: Reply with quote

KTPhil wrote:
61SNRF wrote:
more resistance will increase the firing voltage


I'm trying to figure out how this can be... cold fusion? ;-) A given power through a higher resistance must produce a lower voltage. True for AC or DC. Ohm's Law and all that.

Unless it "loads" the coil differently somehow and increases the current? That's where I start mumbling to myself...


x2

But the coil cannot produce more current - THAT is set by the thickness of the wires used in the windings inside the coil. And the voltage there can't vary - THAT depends on the comparison of the NUMBER of windings in the primary versus the secondary windings.

Ohms law - there is a direct relationship between volts, amps and resistance. Increase the resistance in any circuit and you reduce the voltage.

The only reason for having a set resistance in the spark plug circuit is to reduce radio suppression pulses. The other way to remove these electromagnetic pulses is to completely shield the cables, as is done in piston powered aircraft.
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KTPhil Premium Member
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PostPosted: Thu Jun 04, 2015 5:03 pm    Post subject: Reply with quote

There may be more to it than that... but I'm out of my league to debate. Ohm's Law applies to steady state current flow, and here we are talking about a surge/pulse that varies depending on how fast the electro-magnetic field can collapse inside the coil. I suppose a resistance might vary the pulse, maybe diminishing the electrical energy, but changing the shape of the pulse so the peak is higher? My head hurts...
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61SNRF
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PostPosted: Thu Jun 04, 2015 8:20 pm    Post subject: Reply with quote

Geez, do I have to explain it? You guys need to get off your computer chairs and get out into the lab more often Laughing

We're not dealing with 6 volts here nor even 12 volt for that matter, the Secondary Ignition system's output is measured in Kilo volts, as in thousands of volts. Ohm's Law still applys, but do the math and you will see 1000-6000 ohms spark plug wire resistance can easily be overcome. Just open the hood of your very own car's for an example. As Andy states, not uncommon to see a 5K ohm rotor and 1K ohm wire ends.
1,000,000's of examples running around out there right now, what else need be said Wink

I have first hand knowledge from working on cars professionally since the early 70's where we had to hook up an AutoScan oscilloscope to every car in for service. (Might have to look for one in a Museum now-a-days, that's how old I am Smile )
It's old school CRT will display the primary and secondary firing cycle of each cylinder in a graph of DC voltage over time.

A typical IC carburated 4-cycle gas engine's voltage firing spike with points/coil ignition would be roughly in the range of 25,000 to 30,000 volts. This is only about 50% of the coils ultimate Secondary voltage capacity.
Whether it be a 6 or 12 volts Primary voltage that doesn't matter, this is where the coil's winding wire gauge and length come in. I'm no electrical engineer, so we have to trust those guys on that.

With the engine running, on the screen we would see a "parade" pattern, where all cylinders are lined up in order, and you look for the peak firing voltages to all be nearly equal...
Image may have been reduced in size. Click image to view fullscreen.


If you take a plug wire off and hold it to ground, you will see the voltage for that cylinder go to zero.

If you take a plug wire off and progressively move it 1/8" at a time away from ground, the voltage will rise to the coils maximum capacity, which might be in the neighborhood of 60,000 volts for a good Bosch Blue coil.

So, to answer the OP's question, how much resistance is too much?
If you pull the wire too far away, or in other words add too much resistance , either the coil will not have the capacity to fire the voltage needed to jump the gap, or the spark will seek an easier path to ground, as in right through the spark plug wire insulation to the closest ground.
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KTPhil Premium Member
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PostPosted: Thu Jun 04, 2015 10:03 pm    Post subject: Reply with quote

It's not that we don't know about primary and secondary voltage and the spikes, but it's this part that eludes us as to why:

61SNRF wrote:

If you take a plug wire off and progressively move it 1/8" at a time away from ground, the voltage will rise to the coils maximum capacity.
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All_talk
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PostPosted: Thu Jun 04, 2015 10:50 pm    Post subject: Reply with quote

KTPhil wrote:
It's not that we don't know about primary and secondary voltage and the spikes, but it's this part that eludes us as to why:

61SNRF wrote:

If you take a plug wire off and progressively move it 1/8" at a time away from ground, the voltage will rise to the coils maximum capacity.


Because its ohms law, the voltage has to increase to bridge the larger gap (larger resistance). Like the man said, the coil will respond to the resistance up to the point it can't.

But each piece in the chain like the rotor, plug wire, plug and the plug gap have a resistance and each resistance has a corresponding voltage drop. If you remove resistance in the chain, say going from a resistive rotor to a non-resistor one, the voltage measured at the coil will drop, but hear is the tricky part, the voltage across the plug gap won't. The voltage required to bridge the air is still the same.

In a healthy ignition system, with all other things being equal, removing or adding resistance in the chain will not change the voltage at the spark in the cylinder. The amount of current/energy delivered by the spark is not ruled by the voltage, it's about the design of the coil and how much energy it has stored before discharge.

Gary
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MrGoodtunes
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PostPosted: Sat Jun 06, 2015 2:20 pm    Post subject: Reply with quote

Many thanks to everybody who chimed in on this resistance issue that's been bothering me ever since being unable to find non-resistive plugs. After reading the responses a few times over, and then trying different wires, plugs, connectors and using my VOM meter to check resistance values; here's what I've come to understand:

Ohm's Law (V=IR, voltage V is equal to the product of current I times resistance R) applies only to a steady DC circuit. For example, it applies to the primary coil circuit during the midst of the time interval while points are closed. However, just as soon as points open that circuit, Ohm's Law is not applicable. But this is the crucial moment for any analysis of spark generation. So I thought back to my old AC circuits courses, almost all of which involved sinusoidal AC. So again, like Ohm's Law, not applicable. Most of it, that is. The part that may be helpful is the generalization of Ohm's Law for any circuit:

V = I Z

In the General Rule, Z replaces the R in Ohm's Law. Actually, Z (which stands for "impedance") includes resistance R along with another component of major importance. That other component is called reactance. And all of these quantities are functions of time, except resistance, which is the only constant.

This is where my understanding gets foggy. I know that reactance is associated with something call'd inductance, which can have an accelerating as well as decellerating effect on electron flow. And it's all the result of wires being near to a building and/or collapsing magnetic field. Oh, and one last thing, I'm pretty sure inductance is HUGE in comparison to the effect of resistance.

Bottom line: Resistance is immaterial.

Only two things are at our disposal to affect spark (assuming wires are well insolated, plugs have been "read" for heat range, etc.): namely, coil and gap. BTW, "gap" includes the little jump at the end of the rotor.
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PostPosted: Sat Jun 06, 2015 3:18 pm    Post subject: Reply with quote

some folks have stated the voltage output of the coil is related to among other things the gauge or thickness of the coils internal wires. This is NOT correct. the amplification of voltage by the coil is related to the ratio of number of turns of the primary to secondary coils inside the spark coil. gauge of wires has nothing to do with the voltage amplification. The gauge has to be enough to handle the current flow, but only the ratio of coil turns is what determines the amplification from 6 volts to 20,000 volts or so. in this case a 3333:1 ratio is required to get 6 volts up to 20K volts (20,000 \6 = 3333.3 )

the coil is a transformer for stepping up voltage.

count the coils to obtain the amplification ratio, regardless of wire gauge!!!!
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