My question is-Is this all OK and normal? Is 12.3 volts at coil OK?? Or am I sending too many volts to Points and Coil and in danger of burning up coil/points???
This is long, trying to answer inevitable questions up front.
71 302 convertible Points ignition.
I keep hearing “voltage at the coil and points should be 6-9 volts” but i never see any real concrete info.
I also hear stock wiring harness has resistors built in to bring that voltage to coil and points down.
I am severely confused.
So long story, car is being rebuilt after 25 year storage, maybe a few hundred miles in year of ownership. As part of initial engine review and tune up, I replaced stock coil, it was split and leaking. With Accel super stock, 8140C, 1.4 Ohm. Car ran great, no issues.
Stock wiring harness was toast. I replaced it with an American Autowire full kit. This kit states in instructions you must use a Ballast resistor and Starter Solenoid bypass if you have Points style Ignition. I do have factory Points ignition. So I bough their 1.4 Ohm Ballast resistor and wired inline to coil per instructions. The Car ran great, for 100 miles.
I started getting intermittent loss of spark while running, the first time after 3 minutes, I wiggled coil to Distributor spark lead and it ran again. The next day, I replaced the spark lead because the one I had seemed flakey. It ran, that day, the next day it died on the street in front of my house(2 minutes or less). I replaced the Spark lead again and car would not start. I removed Coil from mount and whacked it medium/light on a hard bracket, car started. I assume I had a bad coil.
During this time, I was testing, I seemed to be getting unstable voltage and Ohm readings from coil. So I replaced it with an identical Accel Coil.
The Car started and has 45 minutes run time with no problem.
During this whole process, I have been monitoring Volts at coil, and either side of Ballast resistor. It seemed like the Ballast resistor was unstable, so I ordered new ones off Amazon…I have a 1.4 ohm resistor in place.
So here’s my readings…
Coil, not running, disconnected, around 1.4 ohms, zero volts. Coil connected with car running 12.3 volts. Coil with key on, but not running 12.3 volts.
The ballast resistor, unplugged, 1.4 ohms. connected, key on, not running, 12.3 volts on both posts. Connected, car running, 14.4/14.6 on ignition circuit side, 12.3 on coil side.
The car’s general electrical system with key on, not running, 12.3, with car running, 14.4/14.6, these voltages also represent the battery volts at rest, and the alternator output while idling. Makes sense to me.
So, summary, Ballast resistor seems to be OK, coil seems to be OK, with matched Ohm readings., ballast resistor seems to be trimming 3-4 volts out of path to coil. But not down to a 6-9 volt range.
My question is-Is this all OK and normal? Or am I sending too many volts to Points and Coil and in danger of burning up coil/points???
Discuss Please!!
Thanks!!
This is long, trying to answer inevitable questions up front.
71 302 convertible Points ignition.
I keep hearing “voltage at the coil and points should be 6-9 volts” but i never see any real concrete info.
I also hear stock wiring harness has resistors built in to bring that voltage to coil and points down.
I am severely confused.
So long story, car is being rebuilt after 25 year storage, maybe a few hundred miles in year of ownership. As part of initial engine review and tune up, I replaced stock coil, it was split and leaking. With Accel super stock, 8140C, 1.4 Ohm. Car ran great, no issues.
Stock wiring harness was toast. I replaced it with an American Autowire full kit. This kit states in instructions you must use a Ballast resistor and Starter Solenoid bypass if you have Points style Ignition. I do have factory Points ignition. So I bough their 1.4 Ohm Ballast resistor and wired inline to coil per instructions. The Car ran great, for 100 miles.
I started getting intermittent loss of spark while running, the first time after 3 minutes, I wiggled coil to Distributor spark lead and it ran again. The next day, I replaced the spark lead because the one I had seemed flakey. It ran, that day, the next day it died on the street in front of my house(2 minutes or less). I replaced the Spark lead again and car would not start. I removed Coil from mount and whacked it medium/light on a hard bracket, car started. I assume I had a bad coil.
During this time, I was testing, I seemed to be getting unstable voltage and Ohm readings from coil. So I replaced it with an identical Accel Coil.
The Car started and has 45 minutes run time with no problem.
During this whole process, I have been monitoring Volts at coil, and either side of Ballast resistor. It seemed like the Ballast resistor was unstable, so I ordered new ones off Amazon…I have a 1.4 ohm resistor in place.
So here’s my readings…
Coil, not running, disconnected, around 1.4 ohms, zero volts. Coil connected with car running 12.3 volts. Coil with key on, but not running 12.3 volts.
The ballast resistor, unplugged, 1.4 ohms. connected, key on, not running, 12.3 volts on both posts. Connected, car running, 14.4/14.6 on ignition circuit side, 12.3 on coil side.
The car’s general electrical system with key on, not running, 12.3, with car running, 14.4/14.6, these voltages also represent the battery volts at rest, and the alternator output while idling. Makes sense to me.
So, summary, Ballast resistor seems to be OK, coil seems to be OK, with matched Ohm readings., ballast resistor seems to be trimming 3-4 volts out of path to coil. But not down to a 6-9 volt range.
My question is-Is this all OK and normal? Or am I sending too many volts to Points and Coil and in danger of burning up coil/points???
Discuss Please!!
Thanks!!
