Hello All..I can't seem to get a answer from MSD..I have a Blaster SS coil and a Proform distributor with a CD modual (ignition box)..(no points) Do I need to use a ballast resistor..My understanding it's for when starting your engine uses 12V and when started it drops down to 6Vs, to the coil??????????? Thanks Duane..
with that ignition,you shouldn't use a resistor.the only reason they use a resistor is to save the points.when I switched to the electronic ignition,I ditched the resistor.
I thought the purpose of the resistor was to limit the amount of current the coil could draw. If you touch your coil after a few minutes and it's hot as a two dollar pistol you probably need a resistor in the circuit with it. Some are made with an internal resistor that limits current, some are made that require an external resistor. Check the instructions for the system you are using. Don't ask me how I learned this little bit of wisdom...
Please, lets here more. I've wondered the same thing. I'm running a Mallory UniLite with a ballast resistor from the old points setup. Would like to dump the resistor but what takes the heat if it's gone ?
Just went thru this on the Track Roadster... some coils are internally ballast resisted; others are not. Ballast resistors are there to allow the ignition to be 'boosted' during engine cranking, thus overcoming the voltage drop ***ociated with current inrush to the starter. Without a ballast resistor, the ignition system is potentially 'short' enough voltage to bridge the sparkplug gap. Most good coils (as far as I know) are internally ballast resisted, which is why this isn't a huge issue nowadays. there was a good website on the subject - do a search on ballast resistors and coil voltage and it should crop up. There's a way to check if the coil is internally resisted - I just went to the counter and asked for an internally resisted coil to save wiring connections, and that's what I got for an extra $18.
I just went thru this on mine. This must be the exception to the rule. I had to keep the ballast on mine but its not for the coil, the coil voltage and trigger are now coming directly from the MSD box, But the points conversion kit in my dist (ACCEL similar to a unilite)recommends using a resistor to the distributor Module or "premature module failure can occur"so I kept it on mine, but its only dropping the voltage to the points conversion kit and really has nothing to do with the coil. You should check with proform if their distributor doesent need it then, no you dont use it
I have a unilite distributor and mallory coil.. The tech rep at unilite says I should run a ballast resistor with my mallory coil unless I have the promaster coil that has the built in resistor. The unilite directions do say that a resistor is required to prevent the module from burning out.. I do not have a CD box so if you run a CD box you may not need one.
Hey, it has to do with the total current draw in the primary circuit, if the module has no current limiting circuitry then the heat (amperage) from grounding the coil (so it will creat a spark when the circuit is opened) wont ruin the switch (be it a set of points or a transistor completing the path to ground. The byp*** circuit during cranking it to provide a hotter spark as during cranking the available voltage is a couple of volts low due to the current draw from the starter and the resistor together, I have not failed to find the information as to use the resistor or not when asking the module manufacturer as the source,I hope this helps.....p.s. use a coil recommended by them as well.
The Jalopy Journal
