Ignition Coil usability question?

[Station]

When the ignition coil went on my Whizzkid, Pete-M brought one round which I think was off some random 80's car like a Jensen or Scimitar.

Basicially, engine twice the size of the one I had! Years and years ago, I went to Demon Tweeks to get an ignition coil for an Astra and was told you could definately not use another coil on another ignition system , but the whizzkid thing learnt me that Demon Tweeks bloke was a bell end who wanted me to buy a 120 quid coil instead of a standard 30 Universal coil, and now I have a load of ignition coils of various cars, and a car not working because it's got a knackered coil!

Is this a case of swapping over as they all have the same connections and all have coil amps (from the same era).

[Pete-M]

It was off a Jensen Interceptor, and yes, it'll work. It's just a bit heavy duty for a Whizzkid.

[simmo]

I thought the point of a ballast coil was that it was 9v (crank voltage on older cars) and on cranking the resistor is by-passed. So I would check if a coil is 12V or 9V and whether it for Electronic Ignition or not.

[dollywobbler]

You can't really just use any coil on any car. All depends on the resistance. As it happens, some Kawazaki and Harley Davidson coils are the same or similar to the spec on a 2CV, so some use those coils.