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Posted By Discussion Topic: coil resistor -- page: 1 2     fenbach 11-05-2012 @ 4:24 PM reply profile send p.m. Member Posts: 227 Joined: Dec 2009 i read that bypassing the resistor will result in more spark for easier starting. why not just eliminate the resistor? is 6V too much for the coil over a period of time? and for that matter, will bypassing the resistor for a few seconds while starting do any harm? or any good? thanks. ford38v8 11-05-2012 @ 5:35 PM reply profile send p.m. Senior Posts: 2765 Joined: Oct 2009 Yes, 6v is too hot for the coil over time. The coil wants 3 1/2 to 4 volts, and the resistor works to deliver that voltage despite varying voltage from the charging system. As the starter motor pulls a great deal of voltage, a resistor bypass will in effect deliver about the same voltage the coil wants anyway, so it's a wash. Some late 40's and early 50's cars had a bypass built into the starter button, and that is certainly possible to do with the Early Ford system as well. It involves the use of a diode from Radio shack, and the diagram devised by our friend Bob, AKA Supereal. Bob, where are you? Alan supereal 11-05-2012 @ 7:30 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 I'm here, Alan. Many people don't understand that the ignition resistor's main function is to act as a voltage regulator to control the erratic level of the car's electrical system as it feeds the ignition sustem. Voltage is the product of current times resistance. The system voltage increases as the generator is spun higher and the nichrome wire in the resistor heats up, increasing resistance. This keeps the coil from overheating, and the points from burning up, maintaining a level ignition voltage of about 3 to 4 volts. It is somewhat crude, but was a master stroke for its time. I do install a diode to compensate for the system loss as the starter is used, and if anyone is interested, I can repeat the instructions. I do a lot of posting, and don't want to wear out my welcome. fenbach 11-07-2012 @ 3:56 PM reply profile send p.m. Member Posts: 227 Joined: Dec 2009 bob, you do post a lot, but all great reading, i'd say. i would like to see the instructions for a "diode to compensate for the system loss as the starter is used." thanks. bob [also] ps you talk about the resistor being a master stroke for its time. i seem to remember a 60s plymouth having a ballast resistor. wonder if that served the same purpose?? supereal 11-07-2012 @ 4:09 PM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 Thanks for your kind words. I'll look for my instruction and diagram and post them again. Many, if not most, of 50's cars used a six volt coil in a 12 volt car. A ballast resistor was used to reduce the voltage, and in some cases, the ignition key provided the full voltage. Others had a connection to the starter solenoid. The idea was to provide extra voltage to offset the system loss caused by the starter. When the starter stopped, the coil was fed six volts thru the ballast. In old Fords, the starter draw can be several hundred amps, causing the voltage at the coil to drop as low as two volts, not enough to make sufficient spark. If your car tends to start just as you release the starter button, you have seen this in action. The advent of the solid state diode made fixing this very easy and inexpensive, and greatly increases starting, both cold and hot. Old Henry 11-07-2012 @ 4:38 PM reply profile send p.m. Senior Posts: 738 Joined: Apr 2010 You can run a line from the terminal on the starter solenoid that goes to the starter to the battery side of the coil, bypassing the resistor. Then, when you push the starter button that energizes the solenoid that then sends current to the starter it also shoots current straight to the coil without going through the resistor. The problem is that, with the key on, after you let up on the starter button the current flows back the other way to the starter from the battery terminal on the coil and keeps it spinning. That's why you have to put a diode in the new line so that the current can go from the solenoid to the coil but not from the coil back to the solenoid terminal. Pretty simple. Get it? Old Henry (The older I get, the better old looks.) This message was edited by Old Henry on 11-7-12 @ 4:39 PM fenbach 11-07-2012 @ 7:20 PM reply profile send p.m. Member Posts: 227 Joined: Dec 2009 yep, i get it. thanks. in fact had thought of connecting the starter post to the coil myself. not realizing the current would flow backwards once the car was running. the reason i never implemented my plan was the fear of the car starting even with the key off, particularly if i somehow accidently engaged the starter while the car was in gear. as it is, i'm using the original starter switch in the floor as a switch to bypass the resistor. i don't use it otherwise because i have a starter button on the dash connected to the solenoid. funny story there [talk about overextending a welcome]. once upon a time i used the original starter switch as a starter button, to ground [and activate] the solenoid. one day the wire to the solenoid came lose and would touch ground when i went around a corner or over a bump. of course, the starter would run but not engage. and the hum it made would stop whenever the car stopped making it impossible for me to get out and locate it. until i put the car at an angle by driving one wheel up on the curb. Old Henry 11-07-2012 @ 7:39 PM reply profile send p.m. Senior Posts: 738 Joined: Apr 2010 fenbach, funny you should tell that story. I just recently had my starter stick on. I had just started it to pull out of the garage to go out with my wife. I was still in the garage with my wife in the car and I just could not figure out what that new noise was in the engine. I got out while it was running and opened the hood and still could not pinpoint it. So, I turned the engine off and IT KEPT GOING!! That was real scary! Finally thought of the starter motor still running, punched the starter button a couple of times and it quit. It still does it once in a while but at least I know what it is and how to stop it. But that first time was real weird. The same thing happened the first time I hooked up the wire from the starter solenoid to the coil as I described. After starting the engine the starter kept spinning (just running on the current going back to it from the new coil wire). Took a bit to figure it out then too. (That was a few years ago.) Old Henry (The older I get, the better old looks.) This message was edited by Old Henry on 11-7-12 @ 7:41 PM supereal 11-08-2012 @ 11:10 AM reply profile send p.m. Senior Posts: 6819 Joined: Oct 2009 OK. I found the "quick start" instructions, and post it here. As to my "master stroke" comment, it was in reference to using a resistance coil to control voltage well before the advent of today's solid state devices such as zener diodes, SCRS, etc, to prolong ignition points and coil life. Today's ignition systems are vastly more complicated, and scarcely resemble those of years gone by, and require a scope to diagnose. ford38v8 11-08-2012 @ 10:09 PM reply profile send p.m. Senior Posts: 2765 Joined: Oct 2009 Bob, something just occurred to me... You need a diconnect in the system for the times you want to crank without spark. Can you count the ways you could die if you forgot that bit? Alan

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