Z1OwnersClub GB

Another quick question that I should know!
Talking about a set of Z900-A4 coils ... Low tension leads (primary windings).
There are two leads on the low tension side of the each of the two coils, one side usually has a yellow/ red wire the other side has black,
The other coil has a yellow & red with the other green.

My question is to do with the swapping of this yellow/ red side with the black...
I am reasoning that the low tension coil has current flowing, say, in a clockwise direction and anti-clockwise, if swapped. I realise that there is a collapsing of current due to the points switching on and off, which allows the the coil to step up the voltage in the secondary windings.
So does this current that becomes pulsating matter if it is travelling clockwise or anti clockwise initially? the difference may be small ... Hence, is there a difference in swapping the connections of an individual coil?

Another quick one. My primary winding measures 5.5 ohms, my secondary measures 14.4k ohm... could these be used with a DynaS.

RegardZ.

Dyna S needs coils with 3 ohm Primary Windings

HowieD wrote:Dyna S needs coils with 3 ohm Primary Windings

I think thats a minimum rating

Pigford wrote:

HowieD wrote:Dyna S needs coils with 3 ohm Primary Windings

I think thats a minimum rating

mine worked fine with Dyna S and standard coils

Hi Garn, if you swap the polarity of a coil,it will still spark its just a step up tranny, but i think you would find the spark jumps from the outside of the plug to the centre terminal,probably bad news for fancy plugs like iridiums.

Paulj...

Thanks for the replies thus far..
I'm still a bit confused about swapping primary wires. I accept that 3ohm is the preferred and that standard you can probably get away with!

I'm interested in Pauljac's comment re bad news for fancy (iridium plugs), re spark jumps from outside to centre terminal? Any more comments on this?
I have seen some car coils marked +positve & neg-ve!

RegardZ.

Why worry about coil polarity?
Because the spark plugs do care whihch way the electrons are flowing in the high tension circuit. The spark plug has a thermally insulated center electrode (surrounded by ceramic). With engine running the center electrode runs substantially hotter than the exposed end electrode. Design of the ceramic insulator determines how hot the center electrode will run, leading to the designation of hotter or colder spark plugs. As electrons go, they love to jump away from a hot surface and fly toward a colder surface, so it is easier to drive them from hot to cold rather than from cold to hot. End result is a difference of 15 to 30 percent in voltage required to make spark "initially" jump the gap on the plug depending on which way it is going. So the spark plug prefers to see a voltage potential that is negative on the center electrode and positive on the end electrode for the very first hop of the spark. Oddly enough, this has nothing to do with polarity of the vehicle electrical system, but it is influenced by the common connection inside the ignition coil.

Maybe i'm over-thinking this ....
Thanks Crofty & PaulJac for continuing this discussion.

The spark-plug is earthed at the engine head spark-plug hole, hence, the spark-plug electrode sparks to the outer edge of the screwed section.

The primary windings have current running thru them let's say from the live wire (yellow/red) to the other wire black or green.

This current flow is interrupted by the "make & break" of the contact points.
Also, this current in the primary windings induces a current in the secondary windings, which is the high tension side and produces a pulsating or ac step up voltage.

My worry is, because the direction of the current in the primary winding may oppose the induced current of the secondary winding, I'm thinking it may thus degraded that secondary voltage. Hence, I'm thinking, for optimum spark, I shouldn't interchange these primary wires.
RegardZ.

From the quick read I did, I think the problem is not in the coils but the spark plug. The spark finds it easier to jump from the centre electrode as it is hotter. So the wiring has to allow for the flow from centre electrode to side one. I think the way you swapped the wires allows the primary field collapse still (just opposite flow), then the induced high voltage in the secondary windings to also be opposed thus jumping from outer electrode in.

I remember starting repairing cars that were positive earth (old Leyland stuff), don't know what that would mean though re the ignition system

Agree with that!