Ignition Coil type

[Trevor_B]

Hi,
I'm seeking some advice on the correct coil type for a grey motor in my FC.
I have several coils to select from but not sure which one is correct. They fall into two categories:
Coils marked with statement "Use with resistor" or others with no marking.

Which one is correct for a standard FC install?
What is the correct voltage that is suppied to the coil (via a pink wire with clear plastic cover I think)?
If I need a resistor, what size should it be and where should it go?

Thanks,
Trevor_B

[craiga]

Trevor,

FWIK the standard coil did not use a resistor, and was connected directly to the battery positive through the ignition switch.

A ballast resistor is used to limit the current that is applied to the primary winding of the coil, lowering current flow has two effects - firstly it keeps the coil windings cooler, and secondly it keeps the points from burning out (less current to switch).

You can use either type, but always make sure if you are using a coil marked "resistor" you put a 1-2 Ohm resistor in series with the Coil positive wire (the one from the ignition). You can buy resistors off the shelf at most auto parts stores like Supercheap. You must remember though that a ballast resistor also drops the available coil voltage, OK with a resistor coil because it has a greater number of secondary windings to make up for the lower input voltage. Use a non resistor coil with a resitor and your car will be hard to start and down on power because the coil secondary output will be lowered.

I did an article on this subject that was published in the NSW magazine earlier this year. Download it from http://www.ctcgroup.com.au/Craig/techextract.pdf if you want more reading.

Cheers,

Craig

[Trevor_B]

Many thanks Craig, that clears up the issue for me. Enjoyed reading the extra material about Kettering as well.
Trevor_B

[mcl1959]

Grey motors used a 12 volt coil with no resisitor
Red motors used a 7 volt coil with ballast resistor built into the wire.
When running a red motor in an FC, you must either use a 12 volt coil or a 7 volt coil with the ballast resisitor.
If you run the red motor 7 volt coil with out the resistor (as I did when I did my first red conversion), you end up burning points out very quickly
Regards  Ken

[Burnsy]

Trevor,

FWIK the standard coil did not use a resistor, and was connected directly to the battery positive through the ignition switch.


You can use either type, but always make sure if you are using a coil marked "resistor" you put a 1-2 Ohm resistor in series with the Coil positive wire (the one from the ignition).  

Craig could you please confirm this, the wire on the positive side of the coil on my Grey motor runs down to the distributor where it joins the condensor and the points via a bolt through the distributor housing

I just checked my manual and you are right, so why is my car still running, what is this doing to my electrics?  If It has been like this for over 12 months (when I purchased the car), should I get a new coil before swapping it back to the correct way?  Would have the previous owner changed something to allow it to work this way or is the current just running the wrong way through my coil?

Cheers,
Burnsy

[Effie C]

Burnsy
Just turn your coil around and connect up with neg to points. Would not have done any harm.

Previous owner has not converted car to positive earth has he, pommy cars used to be positive earth and I remember reading years ago that positive earth cars actually rust less then negative earth cars; cars where changed from positive earth to negative earth to suit the growing trend of electronics (new age things called valves etc.)
If car still has a generator it is very easy to change from postive earth to negative earth and back again. Just a matter of wiring connections and flashing the residual flux in the generator coil windings. (file this under useless information)

Effie C