Jump to content

6v or 12v coil


Guest bea1946

Recommended Posts

Guest bea1946

HELLO,

I HAVE A 46 BUICK RUNNING ON A 12V CONVERSION. I HAVE NOTICED THAT THE COIL IS A BOSCH 12V COIL NOT A 6V COIL. THE ORIGINAL 6V HAD BEEN REPLACED. I AM HAVING TROUBLE WITH CARBON FOULING AND WONDERING WHAT EFFECT A 12V COIL WILL HAVE RUNNING AT 6V.

Link to comment
Share on other sites

Guest wombvette

Think about it. A 6 volt coil operates at about 8 volts with a running engine on a 6 volt system. Most 12V systems use a drop resistor to help protect the points. That drops the voltage to about 8 volts running. Now tell me, what is the difference? The question I have is your 12V conversion. Is the coil running on 6V or 12V? That would determine if you need a drop down resistor. However, either way if its firing, I don't think that's going to have any effect on carbon fouling.

Link to comment
Share on other sites

Guest Bob Call

Isn't carbon foul a sign of a too rich fuel mixture?

In the 12V system the points get the same voltage as in a 6V system during normal operation to prolong point life. During starting the resistor is bypassed.

Edited by Bob Call (see edit history)
Link to comment
Share on other sites

Isn't carbon foul a sign of a too rich fuel mixture?

In the 12V system the points get the same voltage as in a 6V system during normal operation to prolong point life. During starting the resistor is bypassed.

Dumb question here but wouldn't the current (amperage) through the points be twice as high at 6v as opposed to 12v. Wouldn't the points run cooler and last longer at 12v, all things being equal?...........Bob

Link to comment
Share on other sites

Guest wombvette

NO.

V=IR Basic formula. Now plug in the numbers with resistance being equal. So I=V/R If you double the voltage, the Amps would also double. Thats why a drop risistor is added to reduce amperage flow through the points.

Link to comment
Share on other sites

NO.

V=IR Basic formula. Now plug in the numbers with resistance being equal. So I=V/R If you double the voltage, the Amps would also double. Thats why a drop risistor is added to reduce amperage flow through the points.

Of course you are correct. I was suffering from a self induced brain fart. ....Bob

Link to comment
Share on other sites

Guest John W. Cina

Coils also go by polarity. For + or - ground systems.

It has some effect as to conduction taking place in a spark ------ It is refered to as thermionic emision ---- or similiar to the conduction that takes place in a vaccum tube. Current - electrons flow from a heated negative terminal to a + positive terminal ---------- so than we can get confused which terminal of a spark plug is the hottest ??? I guess I'd say not the center terminal ------ may not help you guys but ???

Link to comment
Share on other sites

  • 2 weeks later...
Guest bea1946

Yes you are quiet right and I do have the primary running at 6 volt through

a ballast resistor, and yes it would burn the points to run at 12 volt.

I am not sure that you have understood the question. It is the coil output performance that I am questioning and the follow on effect to the plugs. I did not know if the output from the 12 volt coil system is the same as the 6 volt system, but now I must assume they are. Now, being that all thing are equal as you said. The output from a 6 volt coil is going to have to produce sufficient current from the induced EMF in the secondary coil to have a good spark, from the same resistance of the ignition wires and losses in the distributor and the plugs.

If the output for operation from a 6 volt coil is the same as the 12 volt coil as I assume, say at 15kv, the turns ratio required to produce the output of 15kv from a 6V coil is 1 to 2500 turns not including losses in the coil and back EMF current. The halving of the input voltage to a 12v coil that is designed to run at 12V will only produce half the output voltage. Because the ratio of a 12V coil is going to be half, being 1 to 1250 turns. (15000/12) to produce the 15kv output. So the output voltage from that coil with that turns ratio of 1 to 1250 running at 6 volt input is 7.5kv not 15kv.

There might be a spark, but no where near as strong.

And in that case that will be weak ignition and fouling could be a problem.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...