Resistor plug caps and resistor plugs

I've got two resistors - one in the plug cap and one in the spark plug. Almost.

One of my NGK plug caps went bad, the internal spring that clamps the plug terminal wore out. So, without thinking about it, I bought some new NGK caps at a local shop but when I got home I noticed that they have built in resistors.

I like to run the iridium plugs but it appears that both the Denso and NGK lines of iridium center electrode plugs have built in internal resistors. As far as I can find, they don't list non-resistor plugs.

I wouldn't think that two resistors, one after another, is a good idea. Or, am I wrong?

I found that NGK makes a non-resistor plug cap - LZFH, #207-010, L = 90*, Z = plug body for 14mm thread, F = terminal stud type, and H = complact cap.

I have Tri-Spark's ignition and looking at their site, and at their Blog also, I found that they do recommend a resistor, that they do not recommend carbon core wires, but I do not see a straight out recommendation of copper wire or spiral wound or whatever wires.

My existing wires are fine - silver plated copper wire that the new NGK caps screw into nicely.

Has anyone else gone throught this?
What wires are best?

I suggest that you go with proper copper wire and not use double resistor set up. If the spark plugs are resistor type then do not use resistor caps.
The 'back pressure' of current some electronic ignitions need is rather specific and over resisting will feck up the works. Ohm's resistance need's to be considered.
I use copper wire, resistor caps and non-resistor plugs.
All the best mate.

xbacksideslider said:

ike to run the iridium plugs but it appears that both the Denso and NGK lines of iridium center electrode plugs have built in internal resistors. As far as I can find, they don't list non-resistor plugs.
I wouldn't think that two resistors, one after another, is a good idea. Or, am I wrong?

I have Tri-Spark's ignition and looking at their site, and at their Blog also, I found that they do recommend a resistor, that they do not recommend carbon core wires, but I do not see a straight out recommendation of copper wire or spiral wound or whatever wires.
My existing wires are fine - silver plated copper wire that the new NGK caps screw into nicely.

Has anyone else gone throught this?
What wires are best?

Click to expand...

I suggest you e-mail Steve Kelly (Tri-Spark) as he would be best person to answer these questions.

xbacksideslider , if you do contact Steve Kelly, it would be interesting to know what is reply is if you would like to post it here?

Helical or spiral wound wires provide RFI suppresion without resistors, FWIW am using some MSD Streetfire wires on my bike and they work well with my Boyer ignition...I especially like MSD wires as the universal kits come with a clever crimping tool you can use in your vice. A V8 kit was about $40 or so and should cover my MC plug wire needs for years ;-)

Well, I don't think I have to bother Mr. Kelly as the following link shows the type of spark plug wire that Tri-Spark sells - multi stranded copper wire paired with resistor caps -

http://www.trispark.com.au/home/products/

Since I want to run the ultra fine wire Denso iridium plugs that have internal resistors, I'll use the caps that come without resistors and my existing silver plated multi strand copper wires.

I'm tempted to order a pair of Kelly's improved, long spark duration, ignition coils.