[AJD] Another Plea For Education

Terry L. Hrdlicka th01209 at alltel.net
Sat Nov 27 18:37:06 PST 2004


That's just what I meant to say, but couldn't put it as well as Terry did!

Good grief....Two Terrys on the same list....Trying to answer the same 
question!  Yikes!!!  What can the world be coming to?

Terry



Terry

Terry & Carolyn Welshans wrote:
> Cal said:
> 
> 
>>Man, am I learning a lot about engines from this list.
> 
> 
>>Here's my next question.  What would be the symptoms of a coil with
>>incorrect resistance value?  This is regards a 12 volt conversion.
>>
>>Thanks.
>>
>>Cal Barton
>>Nacogdoches, Texas
> 
> 
> 
> Terry's comments about diagnosing this problem are right on.
> 
> In regards to the question about resistance readings, there are two coil
> windings  in an ignition coil, the primary winding that connects to the
> points on one end and the ignition switch on the other, which has the fewest
> windings and lower resistance; and the secondary winding, which connects to
> the spark plugs via the high voltage wire to the distributor on one end and
> to ground on the other, which has many more turns than the primary.
> 
> If the primary coil gets shorted, it has lower resistance and higher
> current.  Higher current makes more heat, and the condition Terry describes
> happens - a time delay while the coil gets hot.  If the resistance gets
> higher, you get less spark from the secondary.
> 
> If the secondary coil gets shorted, you have a weaker spark, as the shorted
> windings don't produce much of a spark.
> 
> On the other hand, if either one is open, with a broken wire in the
> windings, the spark stops.  This can be from overheating, fatigue, or
> mechanical damage.
> 
> So to test a coil with an ohm meter, measure from the ignition switch lug to
> the lug that goes to the points (marked with a "+" and a "-" ) for the
> primary side and from the case to the center high voltage wire for the
> secondary side.  Compare to another coil for values.
> 
> Hope that helps.
> 
> Terry Welshans
> Homer Glen, Illinois
> 
> "Always do right- this will gratify some and astonish the rest. "
> Mark Twain (1835-1910)
> 
> www.midwestoilburners.org
> www.fokisd.org
> www.terrystoy.com
> 
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