Mallory Distributor Install - the ballast resistor question

Von Dud · Post by **Von Dud** » June 16, 2010, 4:04 pm

Hey Folks - Just picked up Mallory's Unilite elec. ignition distributor (part number 4563101 - mech advance) and coil (part number 29216) for my L6. The related question:

Did Ford use a loom resistance wire between the ignition switch and the coil (+) in their factory harness?

I'm trying to avoid having a ballast resistor stinking up the place while I'm cleaning up the engine room. Thanks for y'alls insight.

Uncle Skip · Post by **Uncle Skip** » June 16, 2010, 6:20 pm

Yes.
Ford uses a pink resistor wire to the coil.
But because the Mallory unit is so sensitive, I'd check the voltage with my multi-meter. Do not use more than 8 volts max to the + side of the coil.
The ballast resistor does not cause any problems.... just mount it out to the way and run a full 12 volts thru it. That's what I'm using for my Pertronix.
U@ss

Von Dud · Post by **Von Dud** » June 17, 2010, 7:42 am

Thanks Uncle Skip - Your reply and level of detail is MUCH appreciated. Will do.

Tip of the hat from San Antonio.

charliemccraney · Post by **charliemccraney** » June 17, 2010, 9:06 am

The instructions for that distributor say to use a ballast resistor. You're going to have to have one somewhere.

Von Dud · Post by **Von Dud** » June 17, 2010, 9:22 am

Thanks Charlie - just to be clear, Mallory's instructions provide for 3 potential configurations: 1) with ballast resistor 2) with a loom resistance wire 3) with an ignition control box.

I will be using method '2' if the resistance wire, provided in the OEM harness, provides a drop to 8 volts to the coil's + connection.

Hope this helps to clarify and thanks again.

winr · Post by **winr** » June 17, 2010, 5:19 pm

Hey Von Dud.

The resistor wire on my 65 f-100 is under the dash.

That makes the coil wire from the fire wall to coil have a voltage drop versus the battery voltage.

Check your battery voltage and voltage coming out of the resistor.

My Ford resistor wire lowers the voltage right around 25%.

With my engine running, I have 14.1 volts at my battery.

At the coil on the + side, I have around 10.5 volts.

Ricky.

Von Dud · Post by **Von Dud** » June 18, 2010, 8:12 am

Thanks Ricky - will definitely spend some time with the multi-meter this weekend. That's great news.

Man alive, Friendswood, Pearland... Texas Slicks represent! My wife and her family is from Friendswood - her folks live on the way to Clover Field. Small world.

Thanks all.

Von Dud · Post by **Von Dud** » June 18, 2010, 10:13 am

Found this in Mallory's Tech Library:

It's not the voltage so much as the resistance on the primary side. You need at least 1.4 ohms (and preferably no more than 3 ohms). While it is true that more primary resistance will reduce the voltage, it is difficult to give an exact voltage because it depends on the output voltage of the alternator. Check the primary resistance of your coil. If it is between 1.4 and 3 ohms, you need nothing else. If it is less than 1.4 ohms, you need to add a ballast resistor or resistor wire (many pre-'74 cars came with a resistance wire from the factory) so that your total resistance (coil plus resistor) is at least 1.4 ohms. If your total resistance is more than 3 ohms it won't hurt the Unilite but your spark will be weak.

http://www.malloryperformance.com/TechS ... ?ID=115008

AND

If your (Ford) is all original it should have a resistor wire. To check, hook everything up and start the engine (without the ballast). Check the voltage at the battery and then at the positive side of the coil. The voltage at the coil must be at least one volt lower than the battery voltage (at the same engine rpm). If the voltage is within one volt, add a ballast resistor. My 1965 Mustang had a resistor wire and I ran a Unilite for years without a ballast.

http://www.malloryperformance.com/TechS ... ?ID=109179

hope this helps folks in the future. thanks for everyone's help on this post.