Ignition coil; heat as evil or resistance as evil

[daveward]

I'm tinkering again, I moved my ignition coil away from its stock position (and the heat of the engine), so now it's as cool as a cucumber. I measured the resistance in the new coil wire just to make sure I had good connections and was flabergasted at the reading. Where 1.000 is bad and .001 is good, my reading was .819. Then I measured other wires of shorter lengths and saw progressive improvement.

So the question is: will the cool coil's power overcome the increased resistance, or would the coil rather be hot with less resistance? Thanks for your feedback.
Dave

 

[IRstuff]

Does it make that much difference? It might matter with a stereo system. but surely the series resistance of the spark gap dominates everything. After all, don't resistor wires for EMI suppression still work?

TTFN

 

[sreid]

You've either got a wiring problem or a measurment problem. 16 ga. wire has a resistance of 0.004 Ohms/ft. (I'm assuming that we are talking about the wire to the coil primary).

 

[IRstuff]

As shown in:

http://www.powerarc.com/sparkplug.htm

and

http://www.magnecor.com/magnecor1/main.htm

the series resistance from the spark plur and resistor wire can be quite high.

I'm assuming that such configurations still work quite well in practice?

TTFN

 

[daveward]

IRstuff and sreid, thanks for the feedback.

IRstuff, as to the question, does it really make a difference...that's basically my question. I take it that you don't think it makes a big difference. Right?

sreid, as to the point about wiring vs. a measurement problem, I believe I've used the wrong terminology...I should have said that I measured the continuity of the coil wire (the spark plug type wire that runs from the distributor cap to the coil). In my case the new wire is much longer than the old one, and instead of continuity being .001 or very close, it was .819. Sorry if I confused the issue. Dave

Dave

 

[IRstuff]

Agreed. The wire resistance should be irrelevant to the spark generation problem.

One note about resistance measurement. There may not be anything wrong with the resistance of the wire. My personal experience is that resistances less than 1 ohm generally require 4-point resistance measurements, as the contact resistance of the probes to the wire will tend to dominate the measurement.

The basic 4-point measurement requires using 2 connections on either end, running a current through one set and measuring the IR drop through the other set. This approach eliminates the contact resistance error in the voltage measurement.


TTFN

 

[daveward]

To IRstuff, thanks a lot for the links to those other websites, they are very helpful.
Dave