1st has spark, the other 3...

[chuck hahn]

Furthermore..why would #1 HAVE spark and #4 not...they are on the same coil. That in itself would point me to the cap and the resistors or a bad plug. But he says he cleaned the plugs and if 1 is firing that also means that set of point and condensor is also working. The process of elimination is pointing toward the caps and the resistors if you ask me.

[sedelen]

Furthermore..why would #1 HAVE spark and #4 not...they are on the same coil. That in itself would point me to the cap and the resistors or a bad plug. But he says he cleaned the plugs and if 1 is firing that also means that set of point and condensor is also working. The process of elimination is pointing toward the caps and the resistors if you ask me.

Yeah, maybe he should swap 1 & 4 leads and plugs around and see what happens.

[ZakDanger]

Good call. I'll swap those tonight and see if I'm getting spark.

[rustybronco]

Dont know about that..Maybe ask Dale to chime in as hes the electrical guru.

I wished! I've forgotten so much over the last 40 years...

It appears the resistors are in place to reduce 'ringing' in the coils secondary system. A resistor placed in line reduces the ringing by limiting or reducing the current flow in the coils secondary. A reduction in current flow would tend to reduce voltage 'overshoot' and oscillations.

See... http://en.wikipedia.org/wiki/Ringing_%28signal%29

Ringing is undesirable because it causes extra current to flow, thereby wasting energy and causing extra heating of the components; it can cause unwanted electromagnetic radiation to be emitted

and another... http://www.ultralightnews.ca/article...psandplugs.htm

This reduces current flow in the spark and it takes quite a bit longer until the energy in the coil has expelled itself via resistor and spark gap. This results in a longer spark. However the spark is weaker due to energy loss in the resistor.

The scope shows this very nicely and it also gives reason why the resistor helps to suppress RF. With the resistor changes in the rate of current flow are much less resulting in "flatter" edges on the voltage vs. time curve that the scope shows you. This implies less high frequency components of the signal in the cable feeding the spark plugs.

It's been a long time since I've heard the term 'ringing'...

[sedelen]

I wished! I've forgotten so much over the last 40 years...

It appears the resistors are in place to reduce 'ringing' in the coils secondary system. A resistor placed in line reduces the ringing by limiting or reducing the current flow in the coils secondary. A reduction in current flow would tend to reduce voltage 'overshoot' and oscillations.

See... http://en.wikipedia.org/wiki/Ringing_%28signal%29


and another... http://www.ultralightnews.ca/article...psandplugs.htm


It's been a long time since I've heard the term 'ringing'...

Thanks Dale,
Now could you put that in layman's terms.
Here's what I get out of it.
A longer and weaker spark, don't think that's good.
Could this have anything to do with RF radiation? Could these be used only for the reduction of noise emmissions to a radio?
I used to have to put special stuff on my outboard ignition circuit to eliminate the buzz on my VHF radio.

[rustybronco]

Steve, The secondary ignition system is basically a spark transmitter with an antenna attached. It is also a resonant circuit (tuned circuit) because of the inductance of the wires inductance and the distributed capacitance of the coil (two wires in parallel is a capacitor). By adding a resistor to an L (inductance) C (capacitance) circuit you reduce the intensity of the oscillation and lower the frequency the circuit resonates.

In layman's term's, you reduce the intensity and move the harmful interference so it won't cause any objectionable operation to other devices.

[sedelen]

Steve, The secondary ignition system is basically a spark transmitter with an antenna attached. It is also a resonant circuit (tuned circuit) because of the inductance of the wires inductance and the distributed capacitance of the coil (two wires in parallel is a capacitor). By adding a resistor to an L (inductance) C (capacitance) circuit you reduce the intensity of the oscillation and lower the frequency the circuit resonates.

In layman's term's, you reduce the intensity and move the harmful interference so it won't cause any objectionable operation to other devices.

Thanks Dale,
OK I'm done with it, I get the gist (I think). In other words those resistors are unnecessary. I thought impedance was going to come up somewhere in the equation.

[rustybronco]

Steve, Next time be nice to me. I'm not an electrical engineer.

[ZakDanger]

Issue fixed. The capacitors were apparently bad. Had a buddy who's a guitar tech and therefore a pretty good electrical engineer take a look at it. First thing he said the caps were leaking.

So new caps, new points, and she fires right up, first kick.