I'm in the process of converting my ignition to electronic. I'm installing a Crane XR-I conversion, Crane adjustable vacuum advance and a Pertronix coil. I tested the vovtage at the coil after hooking up the wires, and had 12 volts on both sides of the coil. Shouldn't that be lower with the built in resistor wire? I checked the voltage at the battery to check the tester, then checked at the coil again. Still had the same reading. What should I do now, install a separate balast resistor? I'm not sure what was done to the electical wiring before I got the car. I know he( the previous owner) had a maze of wire to run the wipers that weren't needed. I was able to cut out probably 3 or 4 feet when I rewired the wipers(the wires went from the switch out through the firewall, then back in, then back out to the wiper motor). So there is no telling what he did for the ignition o No: Thanks Dan :3gears:
Dan, you are going to read 12 volts at the coil with out the engine running with the electrnic unit because you essentailly have an open circuit until you start to spin the dist and trigger the unit. With no ground on the negative side of the coil, no current flows, so voltage stays up at essentailly battery voltage. Jim Burek
Jim I did have a jumper wire connected to ground the negative side of the coil. I have an old Sears tester that told me how to hook up the wire to check it. I think it was right, but not sure. I had 1 wire connected from the + side of the coil to the tester, 1 connected from the tester to the - side of the battery, and 1 jumper wire from the - side of the coil to a ground. Will that still give me 12 volts all the time until it's started? Thanks Dan :3gears:
Well I hooked up all the wires and started it. Then I tested the voltage going to the coil again, while it was running. Still 12 volts going into the coil. I didn't test the voltage on the - side though. Anything else to check? Dan :3gears:
Dan, What are the requirements of the Crane unit you installed. If they don't tell you in the instructions, I would call them, and ask specifically if you need a ballast resistor. The only purpose of such a resistor is to drop the voltage to the coil when the engine is running. The stock GM wiring harness incorporated a calibrated length of resistance wire. This dropped the battery voltage from 13.8 or so down to around 7-9 volts. This resistance wire was bypassed by the starter solenoid while the engine was cranking to supply full battery voltage to the coil for the quickest start. Then when the motor was running, the resistance wire dropped the voltage back for maximum points life. Somewhere in the Crane instructions, they have to cover this, take a look. With the stock points wiring, the ignition switch in the "run position", and the motor off, you should read about 6 volts from the coil + to gound. If you are reading 12 volts the wiring has been replaced. This is commonly done when installing a GM HEI, it needs full time 12 volts. Check with Crane if you can't find it in the instructions.
The instructions said to by-pass the resistor by wiring the Crane unit to before the resistor. What I was concerned about was if that would be ok not running a resistor with the new setup. The setup again is the Crane XR-I conversion, Crane adjustable vacuum advance and Pertronix Flame Thrower II coil. Was it just luck that I had no real problems with this running it through the points with no resistor? The coil I removed was an Accel Super Stock (I think). Thanks Dan :3gears:
Then you are fine, it works with full time 12 volts like an HEI. As for points, they will not last as long without the resistor wire. I guess you changed them often enough, that this was not a problem. Good luck.
I just rechecked the XR-i instructions and you MUST have a resistor wire (or ballast resistor in line) to the positive side of the coil or a coil with a built in resistor. The standard wiring harness had a pink resistor wire built into it. If that has been bypassed you will soon have problems. I do not know if the Pertronix coil is a resistor coil but that should be in your spec sheet.
The Pertronix coil is a low resistance coil. So I need to add a resisitor? How is the easiest way to do this, just add a ballast resistor? I'm pretty sure the original wire was replaced. I have tested it a few times, with it running or not. The results are the same, 12 volts or more( if it's running) at the coil. I'm still working on it for the advance though. I just had it out for a nice 40 min ride. It runs great this way, but don't want to burn it up in the near future. I put the stock advance back in because it would run terrible with the new setup. I think it was just too far advanced. It would run ok with the new setup if I unhooked the vacuum advance. I'm going back out now to work on the new advance. Would it be better to put the advance limiter that came with the adjustable advance in? That would keep it from advancing too far. When I had the new setup in, total advance would be close to 50 degrees. I'll try a few different combos to see what will work. Thanks Dan :3gears:
Dan, Just add a resistor in the line to the coil. If you have trouble starting it cold, run a seperate wire from the "R" terminal of the starter solenoid to the positive side of the coil. When you are cranking the motor, the coil will recieve 12 volts, when you let the key go, voltage will flow through the resistor. The Crane vacuum advance has way too much advance. You must use the limiter. Don't use it the way Crane instructs. Install it like in this picture. It entails drilling and tapping a hole, then use a short screw. Adjust the limiter, so that the distance between the pull pin and limiter is .104 for 10*
You can also limit your stock cannister like this. You must limit the amount of vacuum degrees in the cannister because all your mechanical advance is in early, and the stock amount of vacuum advance overadvances it.
OK, I got a ballast resistor. Where should it be mounted, to the firewall? I see it's porcelain, so it's fragile. I picked it up from NAPA this morning. It says 1.4 on 1 of the posts, so I assume it's a 1.4 ohm resistor. Thanks Dan :3gears:
Dan, You can mount it to the firewall if you like(Mopars do). You can even mount it to the coil bracket. You just don't want it flopping around.
