Topic: 400/4 coil data

[MDW]

Can someone tell me what the primary and secondary ohms/resistance should be for the coils? I replaced both last year with David Silver supplied original manufacturer versions. I wouldn't normally expect them to be bad but I have virtually eliminated all other reasons why cylinders 1& 4 aren't firing. Thanks

[scottly]

The primary should be about 5 ohms, and the secondary should be about 14K ohms +/- without the plug caps. You could try swapping the blue and yellow wires and see if the problem moves to 2&3. If it does, your problem is not the coil. Don't try to start it, just check for spark.

[MDW]

Great thanks. I couldn't find the ohms rating anywhere!

[Bodi]

They should be 5 Ohms (won't measure 5 ohms but close, this is an impedance not resistance). There are 3 Ohm coils that the 400F alternator won't keep up with but DSS would not make that mistake.

[Deltarider]

They should be 5 Ohms (won't measure 5 ohms but close, this is an impedance not resistance). [...]

Can you explain the difference to us?

[Jan187]

Impedance is more or less: how the load under AC currents is seen as a resistance, also expressed in ohms.
Complex indeed , will vary per frequency, and other conditions.

[Bodi]

AC theory is not for the timid. Best to just accept that DC resistance and AC impedance are different in anything except a pure resistive load.