clarification on coil operation

[san_maru_zed]

Just wanted to clear up a few questions I had relating to proper coil operation.

When the key is on "ON" but the engine not going, power should be going into the + of the coil. Should current flow between the + and - of the coil without the engine on? Should it flow between the + of the coil and the chassis ?

When the Coil is firing the current between the + and - of the coil should be "pulsating" right?

Thanks, just trying to sort out why my car has no spark (distributor and coil are fine).

[LanceM]

When the key is on "ON" but the engine not going, power should be going into the + of the coil. Should current flow between the + and - of the coil without the engine on? Should it flow between the + of the coil and the chassis ?

Current will flow between + - if the points are closed. With the points open you should be able to measure 12V between + and chassie ground. If your condenser is shorted you will have no spark and will measure less than 12V from coil + to ground.

When the Coil is firing the current between the + and - of the coil should be "pulsating" right?

Yes it will be but the period will be very short and probably can not be seen using a digital voltmeter, an analog meter would show it better.

No spark if you have 12V to the coil (and haven't done anything like swap distributors) would be usually :

Bad condenser

bad/slipped points

bad coil (usually they leak oil from the hi tension lead area when bad)

[TomoHawk]

I think you'd be better off viewing the voltage with an oscilloscope. I have an ignition analyser with a scope on it that measures rpm, dwell, saturation, etc.

[san_maru_zed]

Thanks LanceM. Turned out my problem was that I had a chassis earth at - coil (didnt realise I wasnt supposed to...).

TomoHawk, that sounds like it would be a very nice setup, a little more sophisticated than my Pencil tester :nervous:

[TomoHawk]

You're right. Using the scope, you can see when the points open & close, so you can tell if the points are bad, and other stuff. I should hook it up to the electronic dizzy on the Z, and read up on what the line should look like.