MSD coil question
Thread Starter
|
Mountain Pass
Joined: May 2008
Posts: 241
Likes: 0
From: Oregon
MSD coil question
Hello. I recently bought a "MSD Blaster 2F" coil from Summit Racing part number 8205. And in the instructions it said that I need to get a 0.8 OHM ballast resister. I went to the parts house and they have a 2-prong and a 4-prong ballast resister. and they have no way of telling me which one I need. I tried calling up Ford Racing but I called to late due to the time zones. I also tried calling Summit Racing's tech line but every time I do I get a busy signal. I'm tired of waiting and I want to run this coil!
My friend has a MSD Blaster 3 coil on his '74 F-100 without a ballast resistor.
Now what I'm wondering about is can I run my MSD coil without the ballast resistor...is it even 100% nessacary? My understanding of a ballast resistor is it is regulator of sorts and doesn't let all of the power through. The reason I went with a aftermarket coil is so I would burn hotter and more efficient.
Any knowledge would be greatly appreciated, Thank you.
My friend has a MSD Blaster 3 coil on his '74 F-100 without a ballast resistor.
Now what I'm wondering about is can I run my MSD coil without the ballast resistor...is it even 100% nessacary? My understanding of a ballast resistor is it is regulator of sorts and doesn't let all of the power through. The reason I went with a aftermarket coil is so I would burn hotter and more efficient.
Any knowledge would be greatly appreciated, Thank you.
Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
Likes: 6
From: Raphine, Virginia
Short answer is if you run 12v full time, coil will run hot and fail. Older Duraspark's sent 12v to start and dropped voltage in run position. The MSD guy's will have to answer about the proper resistor
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
You do need the ballast resistor. It's not a "regulator" in that sense; it's to drop the voltage down from 12 volts using a voltage divider. A full 12 volts will burn it up. If this were me, I'd take my meter to the parts store and measure myself. My guess with the 4-prong is it's a multitap to give you different resistances based on the wiring configuration.
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
If you have the stock wiring harness(In the 84 Bronco?) you already have a ballast resistor in the wiring. It's around 1.0 ohms. So just hook it up. If you add a resistor to the stock harness, you will be adding .8 to 1.0 you already have. If you have run a new ignition wire to the coil, then you will need to add a resistor. Most of them are around 1.0 ohms. If MSD has one that is .8, then you might have to buy it special, but I will warn you, the stock ignition module may overheat with a low resistance and a high output coil.
When the coil is initially energized by the points or the ignition module, it's pretty much a dead short till the field starts building inside the coil. You have to control this surge with a resistance, or the coil will be damaged along with the module or points.
When the coil is initially energized by the points or the ignition module, it's pretty much a dead short till the field starts building inside the coil. You have to control this surge with a resistance, or the coil will be damaged along with the module or points.
