I picked up this Mallory 12 volt Volt Master coil and could use some help with its application. The resistor on the negative terminal has me confused - is it for a 12 volt positive ground system or ???? The only thing I could come up with is that Mallory made them in the mid to late 50's but would like to know more about them. I would sure like to run it if possible (12 Volt, negative ground,points) on my car.
It says 12v on the resistor, just as aside I run a 6v one on my 12v Hot Rod mounted on its side for the last 15 or so years. It works flawlessly ! Gary
That's right but this resistor is an integral part of the negative post of the coil. I don't understand why they'd have that.
See the brass acorn nut ? The one holding the resistor to the coil ? Turn it counter - clockwise & get back to us ...
Yeah okay...fair enough. Didn't realize the resistor could simply be removed. So what would be the purpose of the resistor on the negative side of the coil?? A quick check of an ohm meter with it removed shows there's very little resistance in that resistor - curious of its purpose.
I’m going this route after finding these Mallory paperwork, I have the same coil if I’m dead wrong sombody tell me Fabricator John Miss you dad
Do you have a multi-meter? (If you don't, you should.) The first thing you should do is check the resistance of both the primary windings and the secondary windings. The primary should read something less than 10 ohms, while the secondary should be in the neighborhood of 10,000 ohms (these are rough figures). If either are zero ohms, it's shorted and probably junk. If very high, they are open with the same result. These are originally 6 volt coils (with a primary resistance of 1.5 ohms) while the resistor is usually another 1.5 ohms, giving a total of 3 ohms total (for use with a 12 volt system). Polarity depends on the installation. These are excellent units, and I grab everyone I can find (plus, they look great).
the coil i have a friend got off ebay for me as a bday present its nos in the box with all the paperwork , and a 12v model , the paperwork shows the ballast on the neg side of the coil and it definitely goes there then to the dist, i have a mallory dual point mechanical YB dist with a brown cap, condenser tested good (ebay capicator tester 25 bux) scored nos points and a new rotor , my question is do i need to run a ballast resistor on the ignition power wire ? and run a start bypass off the solenoid for full 12v during cranking ? i will double check the coil Tubman as you said just to make sure all is good if so ill be making a fire this weekend been nearly 2 years doin a cam swap that turned into a full build , fabricator john miss you dad
The points in the distributor ground the current going through the coil. If your vehicle is negative ground, the "Hot" wire from the ignition goes to the terminal on the coil marked positive, while the terminal marked negative goes to the distributor. For positive ground, it's the other way around. Ignition coils are not intrinsically polarity sensitive; they just need to be installed correctly to work properly (although they will work when hooked up backwards). Ignition points can usually tolerate about 4 amps without burning and pitting prematurely. Simply apply Ohm's Law; Current=Voltage/Resistance. 4=12/3 or 4=6/1.5. This is for conventional points ignition; electronic ignitions are above my pay grade.
Probably not. It will depend on the total resistance of the coil assembly. I run that same coil o 6 volts without a resistor. I believe Mallory added the round resistor so they would be able to sell the coil to run on 12 volts with only minor changes. It is interesting to note that I have seen versions of this same coil with the resistor running as a coil of wire in a channel in a round ceramic dick mounted horizontally on the top of the coil. Measure the resistance on the primary windings.
Thank you will do, hope to make a fire tomorrow wish me luck , I’ll report back my findings on the windings Fabricator john Miss you dad
It (resistor) being on negative side means little it's still in series with the points whether open or closed ,it reduces the working voltage to close to 6 and is know as a ballast resistor, it might very well be in the 1 ohm scale (resister)and read less then an ohm on some vom meters. The coil dosnt do any thing except become magnetized when it's circuit is completed by the points closing to ground and open circuit okay the coil produces a high voltage spark when the points disconnect the circuit ! can you hear me disconect...the....circuit. The sparks made from the fold up of the magnetism and somehow causes the voltage to rise several thousand times the 6 or 12 volts primary voltage there are 2 coils inside the coil ( in paralel ) a thicker 6 or 12 volt winding and a very thin high tension spark winding ( thousands of turns wire )( secondary) I supposed it's inductance induced from magnetism and when it shuts up (primary side) the energy in the secondary coil must find a release thus the spark jumps through the coil wire and into every conductor down stream ending at the spark plug or vise versa. A capacitor helps the coil charge or saturate hooked parallel to primary circuit if the capacitor is bad coil won't fire enough to work
Here’s my ohm out results it is a 12v coil and was nos in box so I got my fingers crossed , still wondering if I need an inline ballast on the key on side ? fabricator John Miss you dad
If I read your diagram correctly, you have 1.6 Ohms in the primary windings of the coil and 1.0 Ohms in the integral ballast resistor. 1.6 is about right for a Mallory 6 volt coil, and it looks like Mallory added the additional round resistor for use it with a 12 volt system (which was common practice back then). It should run fine in your application, although the reduced resistance (2.6 Ohms vs 3 Ohms) might lead to slightly accelerated point wear while producing a slightly hotter spark. All in all, not a bad situation. And it looks great too! One last comment. If you are running 12 volt negative ground, things are great. If not some changes may be required.
Ok so I’m good yes 12v neg ground and ya believe a ballast in the power lead (to coil) is not needed I’m happy , actually giddy I’ll post up some pics of my motor build battle but been nearly 2yrs in the making. Here’s a pic first start comin this week , kinda terrifying lol Fabricator John Miss you dad
Good luck with that first start, From the looks of your rig, you should be good to go. In the end, I have always found Mallory components to be of very high functionality and quite reliable. In particular, that coil looks a lot better than most of those I've had.
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