2n 12 volt coil question

[Anonymous-0]

I have a 2n with no spark. It was converted to 12 volts before I got it. I am wanting to replace the coil. Can I wire 12 volts directly from the ignition switch to the coil without any resisters?

 

[Bruce (VA)]

No, it will burn up the frontmount coil. Read the article by Chris Britton; it will give you all the info you need about installing the correct resistors.

http://www.n-news.com/specialads1.html

 

[K.LaRue-VA]

There are some real 12-volt front mount coils out there, but I believe even those need at least and additional 1/2 to 1.0 ohm resistor to survive.

Case-in-point - The 12-volt front mount coil I bought for my 48-8N measured 3.5 ohms. It was a true 12 volt coil and I was told that I did not need a resistor. It lasted about 30 minutes.

kl

 

[Anonymous-0]

How do I tell how much resistance I need?

 

[K.LaRue-VA]

Once everything gets warmed up, the original 6-volt system has a total of about 2.5 ohms of resistance including the coil.

The usual recommendation based on LOTS of field experience is that a 12-volt system needs to have a total of 3.6 to 4.5 ohms of resistance.

I would err on the high side and also try to keep the variable resistor with a front mount coil. The variable resistor starts out at a low resistance of around 0.5 ohms and then warms up to around 1.5 ohms. So, if you have a 6-volt coil (1.0 ohms) and the original variable resistor (1.5 ohms-hot) you still need to add about 2 ohms of resistance or you will probably fry the coil.

Some of the replacement 12-volt front mount coils may have as much as 3.5 ohms. With these, the original variable resistor is usually too much and you will have to replace it with a 0.5 to 1.0 ohm resistor. I don't particularly like this option because you lose the hot spark for start-up the original resistor provides.

kl