resistor for points

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   is my 64  wagon supposed to have a resistor wire or ballast resistor between the ignition switch and the coil?....on most cars with points they used something to drop the voltage to 9 volts...gm cars used a resistor wire....did rambler use a resistor wire or a ballast resistor?..if so where us it located?

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auag85201 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Apprentice Joined: Sep/26/2017 Location: arizona Status: Offline Points: 138	Post Options Post Reply Quote auag85201 Report Post Thanks(0) Quote Reply Topic: resistor for points Posted: Dec/25/2017 at 6:31pm
	is my 64 wagon supposed to have a resistor wire or ballast resistor between the ignition switch and the coil?....on most cars with points they used something to drop the voltage to 9 volts...gm cars used a resistor wire....did rambler use a resistor wire or a ballast resistor?..if so where us it located?

FSJunkie Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742	Post Options Post Reply Quote FSJunkie Report Post Thanks(0) Quote Reply Posted: Dec/26/2017 at 1:25am
	I can't say for certain about 1964, but 1965 six cylinder engines did not use a ballast (ceramic resistor or resistor wire). They also did not use a ballast bypass on the starter relay. The ignition coil is fed full battery voltage through the ignition switch in both the start and run positions of the switch. However, they use a different ignition coil with a higher internal resistance of ~3 ohms because it is designed to operate on a nominal 12 volts as opposed to the more standard ~1.5 ohm coil designed for the nominal 6 volts provided by a ballast. So odds are, your car uses a 3 ohm coil with no ballast. Using a standard 1.5 ohm coil will significantly reduce point and coil life.
	1955 Packard 1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited

Lucas660 Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Apr/16/2012 Location: Vic, Australia Status: Offline Points: 1344	Post Options Post Reply Quote Lucas660 Report Post Thanks(0) Quote Reply Posted: Dec/26/2017 at 6:05am
	I'm sure we went through this a couple of years ago. The ballast resistor is only for v8 models. It is mentioned in the tsm but not clearly stated in the wiring diagram.

vinny Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jan/05/2012 Location: Calgary Status: Offline Points: 2837	Post Options Post Reply Quote vinny Report Post Thanks(0) Quote Reply Posted: Dec/26/2017 at 12:46pm
	I think you will find that the coil gets a full 14+ volts as what comes from the alternator. When the engine in my 64 was installed from another car its coil didn't last very long. A Petronix ignition and coil solved the problem.

pacerman Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jul/03/2007 Location: United States Status: Offline Points: 9057	Post Options Post Reply Quote pacerman Report Post Thanks(0) Quote Reply Posted: Dec/26/2017 at 1:05pm
	Yep coil resistance specs are in the service manual 3.2 - 4.1 ohms for both the L-head and the OHV engines. Joe
	Happiness is making something out of nothing.

tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Posted: Dec/26/2017 at 9:33pm
	coil and resistor (aka ballast, aka ballast resistor) are a matched pair. the use of series resistors came with higher engine RPMs that necessitated faster coil charge times. but then at low speeds the higher-power coils tend to overheat, and so the series resistor limits the maximum coil current. 4 ohm coils at 12V means 3 amps (I = E / R) (i=current, e=voltage). with ignition on and points closed, 3 amps flows, the coil gets warm. a 1.5 ohm coil will have a ballast resistor of 1 to a couple ohms, for a total resistance of 2.5 to 4 ohms, current will be limited accordingly. but a 1.5 ohm coil without a resistor will draw 12 / 1.5 = 8 amps, and get hot and eat the points. more current means hotter spark, faster coil charge time, but badly stresses points and demands fatter wire and good connectors etc.
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com

FSJunkie Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742	Post Options Post Reply Quote FSJunkie Report Post Thanks(0) Quote Reply Posted: Dec/27/2017 at 12:51am
	Solves that. Your car is designed for a 3 ohm (roughly) coil without a ballast or bypass. The coil receives full battery voltage all the time. A 1.5 ohm coil at 6 volts has the same spark energy as a 3 ohm coil at 12 volts, so why do sixes use the 3 ohm coil and V8s use the 1.5 ohm coil if they both run the same? ...because V8s are harder for the starter to crank over. This causes the battery voltage to drop, sometimes as low as 9 volts. A 3 ohm, 12 volt coil operating on 9 volts doesn't have much spark energy, however the 1.5 ohm, 12 volt coil operating on 9 volts has a lot of spark energy. All you have to do is bypass the ballast while the starter is operating to supply that 9 volts to the coil. This temporary overload is not enough to harm anything. Fun fact: the 1.5 ohm, 6 volt coil used on V8s is the same coil used on just about all American cars 1940-1975, even cars with 6 volt electrical systems. 6 volt cars just use the 1.5 ohm coil without a ballast, and of course with no ballast there is no bypass. A 1940 Plymouth uses the same coil as a 1974 Buick.
	1955 Packard 1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Dec/27/2017 at 7:17am
	You can use the 1.5ohm coil, but will need to add a ballast resistor if you do. Best to use the 3-4 ohm coil though.
	Frank Swygert

vinny Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Joined: Jan/05/2012 Location: Calgary Status: Offline Points: 2837	Post Options Post Reply Quote vinny Report Post Thanks(0) Quote Reply Posted: Dec/28/2017 at 12:28pm
	Petronix coils are only .6 ohms and work well with their ignition module. Before I got the Petronix I remember reading 4 ohms on the coil that was on the 196. Swapped it though over 30 years ago from a 58 Case tractor I was getting going at the time. In the end both seemed happy with the trade so I suspect they were the same.

billd Members Profile Send Private Message Find Members Posts Add to Buddy List Moderator Group Forum Administrator Joined: Jun/27/2007 Location: Iowa Status: Offline Points: 30894	Post Options Post Reply Quote billd Report Post Thanks(0) Quote Reply Posted: Dec/28/2017 at 1:15pm
	Be very careful as a ballast resistor is NOT the same as a metal film or carbon resistor and you can't accurately measure the voltage - as that varies with the load of the coil. So saying you get full voltage doesn't mean there is no resistor or resistance wire, depending on your means and device to measure. Best to have it running and measure the DROP across the resistance and figure it out. And resistance wires differ from ballast resistors. This is a topic that is covered on thousands of pages out there, not just here, because it's a universal question - to use a resistor or not to use a resistor with any given coil. And it doesn't matter the car IF the coil has been changed - and not matched to the original. I've seen coils replaced and resistors removed - then the next sucker, uh, owner comes along and puts in a new stock coil and keeps burning things up - gee, what's wrong, it's the correct coil......... well the dope before you put the wrong coil in, had problems, and removed the bloody resistor. If the coil has been swapped, go by the coil. If it's stock and correct for the car then go by what that car should have.
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