Cylinder Matched Coils?

[hddennis]

Auto electronics have always been my weak point but I thought I had a basic understanding. A coil just came on eBay that I normally would be interested in for my 4 cylinder Maxwell EXCEPT this one is marked 8 cylinder use only. Is this just marketing or could there actually be a difference?

 

Howard Dennis

[TerryB]

There is a finite time it takes for a coil to re-energize after it is discharged to create a spark.  The amount of wire used in the coil and it's resistance to current flow which is proportional to the gauge or thickness of the wire used are factors that affect this recharge time.  I would speculate an 8 cylinder coil would require a fast recovery and hence a lower resistance internal wire might be used that could have too much current draw for an electric system designed around a 4 or 6 volt coil.

 

Terry

 

[TerryB]

Thinking of it some more, if the D.C. Resistance of the primary side of the coil is not too different from the the 4/6 cylinder coil it might bo ok in a 4/6 cyl application.  Using a 4/6 cyl coil would probably not work well on an 8 cylinder application for the reasons listed above.

Terry

[hddennis]

Thanks Terry, I appreciate the expert help in getting me to understand this. Do you think it might have something to do with Atwater-Kent's previous involvement with radio which was a more sensitive electronics field. I say that because even though I stated electronics was my weak spot I did spend 13 of my early years selling auto parts as a NAPA counterman and I can't remember a single time I sold a coil marked for cylinder usage.

 

Howard Dennis

[TerryB]

I'm using my knowledge of electronics from schooling I had 45 years ago and that is not automotive based.  You are right about tuned coils in radios and possible tie in to that calculation being a factor in how a coil is designed for automobile use when you make assumptions based on rpm range.  The faster the engine turns the higher the frequency of spark cycle and the more that frequency affects the coil performance.   I suspect there is a point in the coil design where the frequency of spark generation required exceeds the ability of the coil to produce a hot enough spark to make the engine fire efficiency especially when you have more cylinders to supply.

 

Certainly newer coils were designed to operate at higher speeds and the factors I've mentioned must have been overcome, but in the timeframe we are talking the ability to make universal coils was limited.  As I said earlier, I believe you may be able to use the 8 cyl coil in a 4/6 cyl application but not a 4/6 coil in an 8 cyl.

 

Terry