Re: 12 volt or 6 volt coil how to tell difference
 

Ok you lot, Slow witted limey here... most of us have kicking around our workshops a variety of coils like this....
a) coils for 12 volt non ballasted ignition circuits, b) coils for 6 volt ignition circuits, c) coils for 12 volt ignition circuits with a ballast resistor. d) so-called sports coils for 12 volt circuits.
Can we get a definitive answer between us as to how to identify each of them?

Re: 12 volt or 6 volt coil how to tell difference
 

Here's my take.. Very simple

a) coils for 12 volt non ballasted ignition circuits ---- will show 12 v out when put from one terminal to the other
b) coils for 6 volt ignition circuits ---- will show 6v out when 12v is put in one side
c) coils for 12 volt ignition circuits with a ballast resistor ---- will show 6v out when 12v is put in one side due to the internal resistor
d) so-called sports coils for 12 volt circuits ---- will show 12 v out when put from one terminal to the other.

Hope this Helps.

Dave

Re: 12 volt or 6 volt coil how to tell difference
 

You need current flow to get a voltage drop. If you apply x volts in you will get x volts out without current flow.

I find 12 volt coils are marked 12 volts on the case, but this still doesn't tell you if it should have an external resistor. I'd connect the voltage across the 2 primary termianls to determin if it needs an external resistor. If the coil draws about 3 to 4 amps then it shouldn't need an external resistor. If it draws more amps, then add a resistor to bring the current draw down to 3 to 4 amps.

BTW, the markings "DIST" and "BAT" on the coil primary termianls are useless unless you know what the coil was built for as far as battery ground.

Re: 12 volt or 6 volt coil how to tell difference
 

So does this all mean its just easier for most people to throw out unknown coils and simply buy a coil for the proper application?

Re: 12 volt or 6 volt coil how to tell difference
 

Succintly.... YES!

Re: 12 volt or 6 volt coil how to tell difference
 

No, as it's easy to check coil polarity, as has been posted on the internet by the Chicagoland MG club.

I know a lot of people consider changing parts the easiest way to go, but it isn't the cheapest way to fix the problem and often leads to more problems.

http://www.chicagolandmgclub.com/tec...neral/574.html

Re: 12 volt or 6 volt coil how to tell difference
 

Aaaaah Tom, you've started us coil polarity again, you cad!

Re: 12 volt or 6 volt coil how to tell difference
 

A brand new 6 volt coil at autozone costs only $16.00. I guess it depends on what your time is worth expecially if that kicking around coil quits during your next tour.