Vintage Mustang Forums banner
  • Hey everyone! Enter your ride HERE to be a part MAY's Ride of the Month Challenge!

1 - 4 of 4 Posts
G

·
Discussion Starter · #1 ·
Just checking everything out before first starting of rebuilt car. Was picking up a ground that I was not happy with. The + coil lead has continuity to ground. Unhooked the wire and its the coil post itself that has continuity to ground......this just doesn't sound right, is it? The car ran with this coil before the rebuild.
 

·
Registered
Joined
·
2,750 Posts
You're correct, it isn't right. The coil floats and is grounded only when the points close. If the wire to the distributor is off the post, the coil should not have continuity to ground. Here's a couple of tips...be sure you're not reading a high ohms scale on your ohmmeter when reading this post for continuity. An excessively high setting of the range switch can lead to a misunderstanding of the problem. Check the coil by lifting the distributor wire, holding the high voltage wire close to the block (spark plug gap distance) then connecting a wire between the block and a the distributor terminal. Each time you ground the terminal then lift the wire off you should get a good spark. Use insulation beween your hand and the terminals and wire or you'll get a sudden shock. In doing this, the high voltage spark will be about 8,000 volts and there will be about 300 volts on the distributor terminal of the coil. This voltage will only last the duration of the spark.
 

·
Premium Member
Joined
·
19,225 Posts
Try bumping the starter to get your points off to another position, and measure again. If the coil still reads zero resistance, replace it. Coils do go bad.
 

·
Registered
Joined
·
2,750 Posts
One last thought...the coil terminal COULD be grounded if the distributor is connected, the points are closed OR if the points are open and the condenser is bad. Check your condenser with your ohmmeter to see if its bad. On connection, the ohmeter should read low then increase to at least 5 meg ohms or the condenser is bad. Why 5 meg ohms? The condenser is a paper or plastic capacitor and these have very high resistance values once charged. The ohmmeter charges the condenser as it reads its internal resistance. And for you folks that want to say a capacitor doesn't have resistance (has capacitance) then know that it also has resistance and the greater the resistance the better the capacitor! When a capacitor has low resistance or no resistance, its bad...
 
1 - 4 of 4 Posts
Top