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Hey guys I got a question about the ballast resistor. My Mustang has an aftermarket Mallory breakerless distributor in it. I was talking to a friend on the telephone today and he said that the ballast resistor isn't needed for a breakerless ignition. He said the ballast resistor was for the breaker type ignition system to keep from burning out the points. He says that it reduces voltage and current to the distributor thereby cutting down the amount of spark to the plugs. He says this can cause a car to miss fire at low RPM.

He almost had me sold when I got to thinking, doesn't the coil produce the voltage that goes to the spark plugs? Then I'm thinking, well resistors in series do cause a voltage drop. What effect does the ballast resistor have on a breakerless distributor? Do I still need it?

I've replaced mine once and am not totally confident in the PO's installation of the distributor. Anybody have any answers?
 

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Most electronic ignitions do not need the ballast resistor but the Mallory Unilite I think does. Check with Mallory to see how many volts they want going to the coil. I think it is 8 volts. If you send anymore than that it will burn the eye out in the dizzy.
 

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Depends on the distributor and the coil. If you run a stock coil with 12v you'll burn it up. They're only made to run on about 8v. And you're right, the voltage to the plugs is provided by collapsing a magnetic field in the coil. The points are simply the mechanism for collapsing the field. Providing the POINTS with more or less voltage would make zero difference in how hot a spark gets to the plugs (well until the points fry, anyway *LOL*).

Check with the manufacturer of your coil AND distributor (or breakerless system in it), to determine wether or not to run reduced voltage via the resistor wire, or if you should eliminate the wire and supply a full 12v to them.

FYI ... Fords don't have ballast resistors, Mopars do. Fords have a resistor wire. They're the same basic principle, however. The ballast resistor on a Mopar is a (usually) white square block in the engine bay. A resistor wire in a Ford is a thick pink wire under the dash.
 
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