Ballast Resistors and You?

Howdy all, Tim here...Well as some of you have heard...we are coming close to having this thing running. At this point I am running 12V straight to the coil. But is that not a good idea? I am under the impression that in many cars the car starts with 12v going to the coil and then the resistor brings it down to 6v to run on. At the same time I don't remember seeing these resistors on my T-birds...or lincoln...there is one on my Packard. I have heard that the points could fuse together as well if you runn it on straight 12v...I never had this happen to me though.

So does anyone have thoughts on this? Perhaps suggestions on they way they wired it? Could I simply run the cold wire from the starter button to the cold side of the ballast resistor? Then when I hit the button 12v goes to the solonoid and the coil then the constant 6v takes over?
Any ideas would be great....oh and if this is really fundamental/basic remember I'm and idiot.
thanks
Tim
MBL

 

Some coils are set to run on 12 volts, some aren't. Also, some cars (GM), have the resistance built into the coil wire, and trigger 12 volt starting voltage from the starter. That's the reason you will see some cars with resistors, and some without.
The thing is, you DO generally need 12 volts to start (starter draw being one reason), yet 6 volts allows your points to last a lot longer. A ballast resistor passes 12 volts when cold, and cuts back to 6 volts when hot, which makes it the easiest alternative.

"remember I'm and idiot."
No problem, I'm sure the both of you will do fine on this project. Just stay on your meds...

Cosmo

 

Tim, newer cars in the 50's, 60's, all had starter relays and starter solenoids, where you could get straight voltage off of to go to the coil for startup. The old flathead cars only have a foot operated button to engage the starter and no provision for straight voltage to the coil. If you run a wire from the starter button to the coil (as you asked), it would work fine for starting, but when it is running, it will be back-feeding voltage from the coil to the starter (curcuits in a starter relay or solenoid solved this problem). I have a '34 coupe that at times didn't want to start when it was hot. I ran a wire from one side of the ballast resistor to the other side, with a toggle switch in the wire. This by-passes the resistor when the toggle is flipped, as soon as it starts, I flip it back to off, so that all the juice goes through the ballast. You are right when you say running straight 12v will damage the points, they won't last a week, you also could burn up the ign coil. If you are still running a 6 volt system, you could get away with running straight battery voltage through the coil, but not 12 volts. The other cars you mentioned as not having a ballast resistor either had a resistor built-in the coil, or had a resistor wire going to the pos side of the coil. When you buy a resistor, I'd buy a dual ballast for a '74 Mopar (for electronic ign). It has 2 seperate resistors on one block, one is weak, one is strong. That way you can experement to see which one works better, and if one side burns out on the road, you'll have a back-up side to get you home.

 

Thats different than the ballast resistor on my Packard...hmmm? What resistor/part will do this 12v cold/6v hot thing?
Tim
MBL

 

Yes, On my 12 volt conversion on the 37. I rewire the whole vehicle and ran an internally resisted coil . You can find them at NAPA. I have been running this setup with my stock dizzy now for 1-1/2 yrs. with no problems. With this setup simply run the hot power from the ignition to the positive coil side and the negative to the dizzy.

 

So I just get an inertnally resisted coil and be done with it. Run it on the straight 12v. Sounds good to me.
Thanks
Tim
MBL

 

Thanks Grimlok for the heads up on the post. Now just a quick point of clarification. This internally resisted coil is fed by 12v. It will start on 12v and the internal resistor will bring it down after start up. Does that sound right? Oh and according to the earlier post it is AC Delco part U515.
Thanks!
Tim
MBL