Hey guys!!! Been doing some searching and now I'm even more confused than I was before. Here is what I have. I have a 350 chevy and a 4 speed (if that makes any difference). My distributer is a stock points style that I modified to fit a Chrysler reluctor wheel and electronic pickup, and I am going to use an MSD 6AL box. Sooooo..... What do I use for a coil? And do I need to resist the power wire? Also is there any good coils from NAPA or CARQUEST? It seems that a lot of things now a days are made by the same company. But I will go with an MSD or another brand if they are better. Thanks for reading my ramblings!!!!
The coil is 1.5 ohms so will flow 8 - 9 amps when saturated. I would use a 1.2 - 1.5 ohm ballast resistor. The MSD can handle the current but the coil will run hotter without the resistor.
That is a 6V coil I believe. I am sure the MSD can handle the current but I would be concerned about the coil running hot, maybe Bubba has run that combination before. It will obviously run without a resistor but without a current limiting module you will be running the coil t twice it's normal current. Their are low resistance ballast resistors down around the 1 - 1.2 ohm range which will limit the current at low speeds then allow more current at high rpm. If you run it without a resistor check the coil temperature at idle. If it gets too hot to touch you will probably Posted using the Full Custom H.A.M.B. App!
When you use the MSD box, the distributor is just a trigger. The dist. connects to the box and the box fires the coil. I would defer to Bubbas suggestion .or use the recommended MSD coil.
I found info that says the IC12 coil is 2.1 ohms and is used on 6 or 12 volt. It will probably work without a resistor. If it runs hot MSD has a .8 ohm resistor. That would make the coil carry a little over 4 amps. The MSD box can carry plenty of current it's not the weak link. So try it with no resistor, if it runs too hot use a low resistance like .8. Hoop
Breaker Points can only handle 4-5 amps without premature wear. So they used a total of about 1.5 ohms coi resistance (12 Volt) and a "ballast resistor". A ballast resistor is dynamic, meaning it has high resistnce at idle and low rpm and less after abut 3,000 RPM when the coil cannot reach full current. This helps keep the points alive. HEI limits the current in the module to about 5.5 amps, it uses a low resistance coil to reach higher current and charge faster. MultiSparkDischarge fires the plugs multiple times at idle until it runs out of charging time. The coil will let you know if it is handling too much current by getting hot, overheating, or shutting down, or melting. That would depend on the severity of the problem. Hoop
Don't think you need a resistor. As joel said, the MSD unit will take care of saturating the coil. I have a MSD 6A on my O/T car and IIRC there's two leads (orange/black) going to the coil. You want a full 12V going into your MSD box for the main power lead (the thick gauge wire). The thin gauge IGN wire comes from your key switch and doesn't need a full 12V to keep the MSD unit on. Just pick a coil from that compatibility list and run it!
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