Posted by arthur on Shelter Island [67.84.143.155] on Tuesday, August 05, 2014 at 09:34:07 :
In Reply to: Re: how to run compression test posted by and [71.202.173.184] on Monday, August 04, 2014 at 23:11:14 :
Let's be sure that we are all talking about the correct wire.
"Primary wire" is the "hot" 6 or 12 volt lead to the coil. It is switched ON with the ignition switch.
The primary circuit is completed (coil energized) when the ground is supplied by the points.
Secondary (hardly ever called that in automotive work) is the high-voltage wire that runs from the coil to the distributor, and then to the selected spark plug through the rotor.