[TR] Testing ignition coil: what am I doing wrong????

[spamiam at comcast.net]

I am trying to test a regular 12v ignition coil that is for my TR4A.  I want 
to test it on the bench to eliminate other causes of no spark.

I hooked the (+) terminal to a 12V battery, and hooked a coil wire to the HT 
side, and grounded the body of the plug.

I then took a wire going from the (-) terminal of the coil and shorted the 
wire to ground, then broke the ground.  I expected a big spark from the plug 
as I broke the ground, but got nothing.   I did get some sparks from the 
ground wire when I broke the ground and a volt meter on the (-) terminal of 
the coil went from zero with the wire grounded to +12.5v when I broke the 
ground.   I also tried a spark tester instead of the plug, but even a small 
gap, one for "small engines" had no spark.  The voltmeter on the (+) side of 
the coil barely flickered when I made and broke the ground on the (-) side. 
It was reading 12.5V all the time on the (+) terminal.

I took some old used spares and also got no spark.  These old units could be 
bad, but as far as I know they are fine.

What am I missing?   I am on the digest version of the forum, so please feel 
free to reply directly to me too!

-Tony