CDI IGNITION COIL RESISTANCE VALUES

[BILLY BEAN]

Does anyone know what the primary and secondary resistance values should be for a healthy coil on a CDI set up?

Thanks Kirk

[AndrewSlater]

Taken from this useful CDI resource
http://forums.pelicanparts.com/porsche- ... atics.html

Primary resistance 0.4 ohm to 0.6 ohm
Secondary resistance 650 ohm to 790 ohm.

Hope that helps
Andrew

[BILLY BEAN]

Taken from this useful CDI resource
http://forums.pelicanparts.com/porsche- ... atics.html

Primary resistance 0.4 ohm to 0.6 ohm
Secondary resistance 650 ohm to 790 ohm.

Hope that helps
Andrew

Thanks for that. I was unaware of the Pelican resource.
I have two coils.
Coil 1
Primary resistance 0.6 ohm
Secondary 0.697 K ohm
Coil 2
Primary resistance 0.6 ohm
Secondary 0.930 M ohms

So secondary resistance appears to show a problem with one or both coils?
Is there anything "special" about a coil suitable for CDI? Will any coil do?

[Lightweight_911]

Kirk - as far as I'm ware, any ignition coil that you use with a Bosch CDI unit needs to have their primary & secondary resistances within those specified limits.

If you do a search on DDK you'll find previous threads on the subject including details of possible alternative coils that may work with the original CDI units.

[AndrewSlater]

Coil 1 looks good but coil 2 is out of spec on the secondary.

The CDI coil is technically a transformer rather than a more traditional coil used in points only cars.

The key parameter is the turns ratio, 100:1 is normally quoted.

Your CDI box nominally puts out nominally 350V so that gives 35kV at the plugs.
I'm sure Johnny will be along soon to give you more guidance.

Regards
Andrew

[BILLY BEAN]

Andy and Andrew,
Thank you very much for your contributions. Most helpful.

Regards
Kirk