Generally i understand that there was a ballast wire under the dash of a 65 Cat. So no need for an external ballast resistor. But, I am having issues identifying if i have the ballast wiring or not. When I bought the car it had points and an external ballast resistor in line before the coil. So i guess maybe it had been rewired and does NOT have a ballast resistor wire. Safe assumption maybe? I replaced the ignition system with a HEI and a MSD Blaster 2 coil, it now has no external ballast resistor, and it runs fine. I'm still presuming at this point that i do not have a ballast wire, so i guess i am putting a full 12v at the MSD Coil, its Primary resistance is .7 OHMs, secondary resistance 4.5K OHMs. Is this ok? Or, do i maybe need to add the external ballast resistor back in line? Today i tried a standard 1.5 ohm coil with no ballast resistor and it went bad real quick, the external regulator got hot and the alternator did too. The alternator fried and is now causing issues with the regulator making it click, and the ignition lights being on all the time. So, I'm definately thinking now that i dont have a ballast wire in the system. Im going to have to get the alternator fixed :-( Im soon to go with a Pertronix ignition built into the standard distributor, so im thinking of this - Using the external ballast resistor Using a Pertronix Flame Thrower Coil with 0.6ohm resistance What does anybody think of this. Sorry, im trying to learn the ins and outs of ignition and also whats been done to my car in the 40 odd years before i got it. What would be your recommendations for Petronix as i have bought this already and its going in soon. Cheers Andy
Sorry to say Pertronix is not well liked here. They have had various product quality over the years. If you have an HEI and a working Blaster coil, why are you messing with this? You can always just put a volt meter on the ignition wire coming from the ignition switch. In my cars (1968) the factory resister wire is encased in a braided white jacket. FYI.
Check for Around 8-9volts to coil with ballast wire pertronix recommends full 12 volts but will work on 9 volts. Never had any problems with them 4 different cars over 15 years
NO assumption is "safe". Measure the voltage at the coil WITH THE ENGINE RUNNING, and compare to the voltage at the battery or alternator. If you have nearly the same voltage at the coil + terminal as at the battery/alternator (Perhaps one or two volts less) you don't have a ballast resistor in the system. If you have more voltage drop--let's say 8 or 9 volts at the coil + terminal when there's 14 volts at the alternator--you have a ballast resistor or really-faulty connections. Don't "guess" at the voltage. Measure it. There is NO reason to put a ballast resistor on an HEI. None. Don't do it. There is NO reason to use a high-resistance coil with an HEI. You're giving-up spark power and potential RPM. Don't do it. Unlikely that the ignition coil has anything to do with the failed alternator/regulator. If this were me--and it has been in the past--I'd scrap the ancient 10DN alternator and external regulator, and make the simple and easy conversion to a 12SI alternator and internal regulator. More power at idle, fabulous reliability, near-OEM looks. You'll need a wire-harness pigtail and you'll have to splice two wires, keeping track of which is which. And you'll need two short jumper wires, connected to the correct terminals of the old external-regulator wire harness. Pertronix is junk. Don't put a ballast resistor on a low-resistance coil. If you HAVE to use Pertronix, FOLLOW THEIR INSTRUCTIONS for whether or not to use a low-resistance coil, and/or a ballast resistor. You're WAY BETTER OFF with the HEI. I have no idea why you'd spend more time, money, effort, and enthusiasm to downgrade the ignition system. HEI is ten times the ignition system the Points system is, and five times the Pertronix systems.
A very basic rule of Thumb in electronics is that if you power something on less voltage then it’s designed to run on, even though it may work, it will run hotter and have a shorter life span!
i have had my petronix in for 10 years now, i have not changed a thing, runs great, starts fast, no problems and it runs a dual carb 425 here is how it runs
