Is there any special coil needed for a duraspark ignition? I'm making my own harness so I dont want to use the factory big plug on the coils.
What's the difference? I notice the msd is the same for duraspark just has the plug instead of screw terminals
In stock application the ignition had a resistance wire of 1.25-1.35 ohm resistance. The Duraspark II coils had an internal resistance of around 1.17 ohm. You can use any aftermarket coil that is between 1.0 and 1.5 ohm and you shouldn't have any problems. Along with that a 1.0 to 1.5 ohm ballast resistor should be used in the run side of the ignition, with no resistor on the start side. I know guys hat have run without the ballast resistor without any problems but I'm not sure what the long term effect will be. Additionally I know a guy who has run one with a 3 ohm coil and no resistor for years and it works fine, but is a little harder starting than it should be.
Correct me if I'm wrong here, but an aftermarket 12v coil and a 12v supply are recommended. With most points style cars you only have 6-8v going to the coil. I've been told the easiest way to get 12v to the aftermarket coil is to use the original wire (+) to kick a Bendix style relay that will send 12v from the battery (with an inline 20a maxi fuse) to the coil. I'm trying to get this down pat myself and here's my cheeseball plan...I hope it's right.
Your idea will work but you are overthinking it. In the stock application duraspark II had a resisatnce wire so there is no reason to by pass it. As for the full 12v for starting, you can pull that off the IGN terminal on the starter relay. The white wire, which is the retard is not really necessary and in fact some years don't even have it. If it seems that the starter motor is laboring, then hook it up on to the IGN termianl as well.
Blaster II is only .7 ohms, a little low, but I think it will work OK. You can also use PerTronix Flame Thrower 40001 (chrome) or 40011 (Black) which are 1.5 ohm
As usual, I'm confused again. I thought that the old "points" coil supply wouldn't provide the correct power to the coil for DS?? I swear I've heard 20 different opinions on how to hook DS up...I'm about ready to say screw it and order Pertronix ign.
I've run the duraspark dist on two engines with blaster coils with the 10-32 threads and nuts. No ballast resistor and no problems. Later, on both engines I substituted an MSD box for the dura-spark box. direct replacement. No resistor. On one of them the MSD got flooded and died. went back to the Dura-spark box. On one of them I needed to add a diode on the alternator excitement wire to be able to shut the engine off. Delco Alternator. Feedback from Alt to ignition.
ok i guess i need to do some more research on the duraspark set up. im getting ready to buy all the parts for this set up. i will have a new reman dist. , new ignition box, small wide male cap and new plugs and wires, just have to get the coil part figured out. we keep msd or accel at work but im not a fan of accel. or stockers.
I ran duraspark for years on my 351c without a resistor and an accel superstock coil at 1.4 ohms. Currently have a superstock on my 351w fitted with Duraspark. It's sparks and has no issues. So, there you go.