I decided to check my coil and I am a bit confused. I used my volt meter to check the coil. I grounded the volt meter to the battery, then used the positve lead to check the coil. On the positive side of the coil I have 14.89 volts (car running). on the negitive side I show +8 volts. Hot on both sides?????? I then took the negative lead off the battery and checked the coil using it's positive and negative posts and got a +9 volts. I checked the voltage of the coil at the tower (car off) and got +9 volts. Is my coil leaking?? Could I have something hooked up wrong? Should one side of the coil be ground and the other positive. Why would I get positive voltage from both sides??? The car runs Ok. I should add that I am by-passing the ballast resistor and I am using the PROTRONICS IGNITOR module.

 

I'm not sure whats normal. Never really thought about it
the 14.89 is the cars charging voltage (no resistor)
The 8 volt measurement is showing the voltage drop across the coil
and the 9 volt measurement should be the same as the 8 volt(same measurement from different points) I'm no expert. but sound ok.

 

Your coil is operating as designed. If you were to connect a oscilloscope to the circuit you would see a sawtooth waveform of voltage. The points (or in this case a electronic module) is turning on and off the voltage to the coil at such a rapid rate a voltmeter cannot keep up, so what you see is an "average" value of the waveform.

The ballast resistor is in series with the coil, it is designed to reduce the voltage across the points to extend their life. During engine start (that is while the starter is cranking the engine) full voltage is applied to the coil. When you release the key to "run" the resistor is back in the circuit.

Hope this helps.

 

The crazy part of all this is we (vette owners) are mostly all the same. We'll work our tails off fixin' sumthin' until we're done and then look for stuff to fix when it's all good. :lol: :lol: I hate myself for doing this, but I can't seem to help it. Must be the chemicals in fiberglas seeping out.........need the fix. :cheers: Ahahahaaaaa..

 

Yep.

Fix it 'til its broke.....one of my enduring mottos........ :eek: :rolleyes:

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Jeff
Ô66. Modified L72
ÒThe Silver BeastÓ
Keep on :D :cheers: :seeya

 

"Fix it till it's broke"
Sounds about right. Thanks for all the info.
Mark

 

Mark, The first thing that came to mind was when you said you had 14+ volts at the + side of the coil, I was going to tell you that someone had bypassed your ballast resistor. Then at the end you told us that you had removed it! Drat!
Seriously though, Your readings sound about right. The primary windings of your coil and the secondary side share a common internal tap, so reading voltage at he secondary would be expected. The voltage difference between the + and - side of the coil would be the voltage drop caused by the internal resistance of the primary coil windings.
With the Pertronics unit it is very important that you do not exceed the current rating of the unit and the best way to do this is read the resistance of the coil and calculate the current draw ie: 12v/1.2 ohms resistance = 10amps of current flow. From the information on their tech board it shows that this exceeds the 8.5amp max current flow for the module. In this case adding a .3 ohm ballast resistor to the circuit raises the total resistance to 1.5 and lowers the current draw to 8.0amps, which falls inside of the reccomended operating parameters.
This example by the way is a solid axle car with a 091 coil, and as you see that to bypass the resistor on this car would exceed the manufacturers reccomendations and would cause prematuture failure of the module. The only reason I point this out is that the question of wether to bypass the resistor is not a simple yes or no question, it depends on the coil that you are using. I apoligize for offering such a long-winded answer to a simple question, but I hear people complain about the modules going bad after a few weeks and you find that they overloaded the module.


:seeya

 

The instructions stated that a balast resistor was not needed if you use a certian coil. The auto parts store recomended the Accell. I checked the voltage out of the coil tower and it was 8.8 volts. I have been running it for about a year and a half now and have had great results.
Mark

 

Your coil is OK. Pertronix has primary coil resistance ratings that they want maintained. Some old Delco coils do not match their specs. The problem with original C1/C2 coils is that they were made to be used with resistor wires and nonresistor plugs or vice versa. Most modern plugs are resistor and so are the wires, which will overload the old coils. To save my original coil, I bought the Pertronix coil that they recommend for the ignition module. It's a lot cheaper than the original coil, and I can feed it R46 plugs with Accel shielded resistor wires.

 

gentlemen
i am using an ACCEL coil [model unknown] that was put into my system by the previous owner. i AM using a ballast resistor. any ideas as to how i can find out if the coil i am using requires a resistor [is there any kind of e-mail tech supprot]?? i want to avoid a weak spark if possible. :confused:

 

Get the model number off your present coil, and go to the auto parts store and look at the new ones on the shelf, they are probably the same thing. But chech to make sure. If the coil is really old, change it. I change mine about every 5 years. The Coil I am using with the protronics is the Accell Super Coil, it is yellow (paint black) and is the same size as the stock one. Accell makes another supper coil that is about the size of two 6 volt batteries, very large, you will know wright away it is the wrong one.
PS:
The heat shortens their life more then miles.
Mark