Is there such a thing as a weak coil?

[Fred]

I have a '64 300hp conv and recently discovered the ohm reading in my 087 coil is very different than a standard over-the-counter coil. Additionally, spark plugs have only been lasting about 250 miles before prematurely fouling on a newly rebuilt engine. Ohms readings on my 087 coil are 7.7 while readings on my standard coil is 6.6. It appears the 087 coil has more resistance thus not allowing the proper amount of energy to flow to the plugs. When I replaced the 087 with my standard coil the engine started running on all cylinders again. Anyone else had this kind of problem? Everything in my ignition system from spark plugs to ballast resister is new. Really puzzled.


Fred

[mike hom]

Re: Is there such a thing as a weak coil?

A "weak coil" would be caused by some of the windings being shorted. This leads to less inductance, thereby less spark and the terminology "weak coil". Yes, it is possible.

[Fred]

Thanks!

Thanks for your response; just as I suspected.

[Jack H.]

Also....

Checking winding resistance (specs should be in your shop manual for the 087 coil) does NOT guarantee coil performance. This simply tells you whether or not the windings are there and intact. If coil had run low on internal oil and core laminations of the transformer are 'fried' you'll lose magnetic coupling efficiency (primary to secondary electrical energy transfer) and see the kind of 'funnies' you're seeing.