basic understanding of coil

[bo dawg 516]

I'm not getting fire to the spark plug but I did see some spark at the points when I looked there. So if it was enough spark at the points why don't I have it at the plug?

I have juice on the positive post with key on and when turning engine over I have juice to the negative post so I assume coil is ok. Could it be the condenser then?

I'm not much up on understanding the electrical, just enough to get in trouble.

Thanks :thumbs2:

[rmaynard 15,938]

The spark that you see at the points is only 12 volts. You see it when the points open and break the 12 volt circuit.

You need to have 12 volts at the (+) terminal of the coil, properly adjusted points and a good condenser connected to the (-) side. Then, with every rotation of the engine, as the points open, you get high voltage (20 to 30,000 volts) from the top of the coil, through the HV wire and to the plug.

If you have +12 volts to the coil, and the points and condenser are good, then the problem has to be spark plug, HV wire, or coil.

[squonk 42,720]

If you have a 12 v test light put the light on the negative terminal of the coil and clip the light's wire to ground Turn the engine over. The test light should flash on and off as the points open and close. If it does not, your primary circuit is not collapsing and the coil will not produce the high voltage needed to fire the plug. Ck points for burning/ arcing and check your condenser.

[bo dawg 516]

If you have a 12 v test light put the light on the negative terminal of the coil and clip the light's wire to ground Turn the engine over. The test light should flash on and off as the points open and close. If it does not, your primary circuit is not collapsing and the coil will not produce the high voltage needed to fire the plug. Ck points for burning/ arcing and check your condenser.

Yes, when I put the test light on the negative post while cranking the engine over it does flash on and off. So I will replace the condenser and plug and try the cheapest way first.

I thought I was on the right track.

Thanks guy's! :dunno:

[squonk 42,720]

If your test light is flashing and the condenser and plug don't fix it, I'd say you need a coil.

[bo dawg 516]

It ended up just being the plug. Cheap autolite brand. Condenser for that thing is $17 But its running now!