Coil Overheating

**Philip P.** · December 28, 2011, 07:54 AM

Re: Coil Overheating

Larry,
Are you running the ignitons shielding and what type of wires are you using. The reason I ask is I had a similar problem and the car seemed to run better with the shielding off. I replaced the wires I had installed (Pertronix wires) and it seemed to go away. I did not take any temperature readings. One thing it will not be the ballast resistor(bypassed) as it is not used with the Pertronix if it is installed correctly they use a full "12 volts" for the module and their coil. The coil should not be that hot anyway I would make sure there are 12 volts to the coil.

**John D.** · December 28, 2011, 08:10 AM

Re: Coil Overheating

Larry, Didn't you say to me that you are using a ballast resistor?
I would can the entire electronic setup you have and either go back to stock on use the good one wire set up. John

**Larry B.** · December 28, 2011, 11:34 AM

Re: Coil Overheating

Originally posted by John DeGregory (2855)

Larry, Didn't you say to me that you are using a ballast resistor?
I would can the entire electronic setup you have and either go back to stock on use the good one wire set up. John

Hi John, I am using a ballast resister. What brand is the one wire set up? Larry

**Philip P.** · December 28, 2011, 01:35 PM

Re: Coil Overheating

Larry you may want to check the voltage there may be something else going on here. I reread your post and both coils heating up could be either the module or the voltage being incorrect (13+ volts on a fully charge system). May be worth a check to make sure, the voltage is proper for the module and coil no matter what brand. Pertronix says their coils do not need external resistance as it is built in. I have heard both sides of the Pertronix good and bad. I have one installed and gives satisfactory performance, although in hindsight the regular point type that are in these cars served well and still do pluse they are pretty easy to set up.

**Philip P.** · December 28, 2011, 01:47 PM

Re: Coil Overheating

Larry forgot to mention Grounds. If not properly grounded or if there is some resistance in the ground circuit that can cause all kinds of problems. I hope this some how helps. Just a few thoughts anyway.
Phil

**Larry B.** · December 28, 2011, 02:40 PM

Re: Coil Overheating

Phil Voltage seems to be correct.

**Philip P.** · December 28, 2011, 03:13 PM

Re: Coil Overheating

Larry, The Pertronix that I have is a 1182LS and uses the acutal distributor lobe to switch the module, not knowing what type you have but being it is 10 years old I would think it is the type with an adjustable gap or window, there may be a problem there causing the module timing to be wrong either to long or short. If it is adjustable I would check that, if all looks correct then I would suspect the module, I would doubt that two coils are bad. The ballast resistors "normally" opens when they go bad so with the original coil I think you should have some where around 8 volts (coil side)when the car is running. Remember when the car is being started the coil gets battery voltage (12V) from the starter and once started the ballast comes into play and the coil voltage is from the ignition switch thru the ballast. I noticed that yours is Fuel Injected car, there may be differences in the circuit but I could not see it on the wiring diagram.

**Larry B.** · December 28, 2011, 03:39 PM

Re: Coil Overheating

Originally posted by Philip Porter (53007)

Larry, The Pertronix that I have is a 1182LS and uses the acutal distributor lobe to switch the module, not knowing what type you have but being it is 10 years old I would think it is the type with an adjustable gap or window, there may be a problem there causing the module timing to be wrong either to long or short. If it is adjustable I would check that, if all looks correct then I would suspect the module, I would doubt that two coils are bad. The ballast resistors "normally" opens when they go bad so with the original coil I think you should have some where around 8 volts (coil side)when the car is running. Remember when the car is being started the coil gets battery voltage (12V) from the starter and once started the ballast comes into play and the coil voltage is from the ignition switch thru the ballast. I noticed that yours is Fuel Injected car, there may be differences in the circuit but I could not see it on the wiring diagram.

Phil, You are correct I have the 1181 or magnetic ring pertronix. Would the 8 volts running be measured at the - coil terminal? If I replace the pertronix I was gong to use the 1181 again. Is the 1181LS any better and can it be installed without removing the distributor?

**Philip P.** · December 28, 2011, 05:08 PM

Re: Coil Overheating

Lsrry, mine is indeed a 1181LS the LS is lobe sensor, you do not have to remove the distributor to install it but you may have to remove yours to get the 1181 out I am not sure on that. If you are using a stock type coil, not Pertronix, then the voltage to the coil + side should be somehere around 8 volts when the car is running. After is is started it runs thru the ballast resistor dropping the voltage. The reading may be a little lower than the 8 volts. The - (neg) side of the coil is where ground is when the module or points close.
As for the 1181 and the 1181LS being different when I talked to Pertronix he said the only difference was the 1181LS was easier to install as the distributor did not require being removed. IN reality I took mine out and installed the as is was easier for me to see what to do and the timing needs to be rechecked anyway and as long as the engine is not truned over while it is out and you mark the rotor position it goes back in easily. I also used the Pertronix coil so the ballast is really just a "tie" point for the module and the coil.
In thinking about your problem the ground for the distributor is thru the housing gears etc it would be intersting to temporarily put a ground wire from the outside of the distributor to the engine block and see if that make any difference. It "should" be grounded properly with the way it is normally installed in the engine but grounding is such a problem with Corvettes. I am not sure what the hold down on a FI car is like but on mine it is a metal bracket and is painted that in itself may cause problems as the ground to the manifold has to get thru any paint and if not painted may have corrosion. All of this may not be a problem but it could be a place to look.
Hope this helps some did mean to be so wordy!!!!!
Phil

**Larry B.** · December 29, 2011, 02:13 PM

Re: Coil Overheating

I took voltage reading with the car running and with the engine off. I just put a new ballast resister on. What are your thoughts of the readings?

Running: 12v resister side=14V low resister side=12V + coil=12V

Off/Ignition On: 12V 9V 9V

+ coil is wired to low voltage (output) of resister

**Tom P.** · December 29, 2011, 08:08 PM

Re: Coil Overheating

I've been running the 1181 on the 56 for years with the PerTronix Flamethrower coil. I left the stock ballast resistor in place, NEVER a problem. A couple of years ago, I ran a jumper wire across the resistor terminals.
This was the result---------------------the jumper wire is coming off!!!

**Philip P.** · December 29, 2011, 10:19 PM

Re: Coil Overheating

Tom, That is interesting, the Pertronix people say to run the coil with battery voltage, they say the resistance is built in. I measured mine it is 1.5 ohms on the primary side I measured a pair of stock coils the 3.1 and 1.8. This indeed may be a problem that will show up in time for all that have used these Pertronix systems. Larry system is 10 years old, mine is about 3 and still seems to be working but time may not be on my side. Did you happen to contact Pertronix? I also wonder what affect having these(Pertronix coils) under the shielding has in keeping the heat from disapating.
Phil

**Philip P.** · December 30, 2011, 07:00 AM

Re: Coil Overheating

Larry, In thinking this over the coils are made to run at 12volts(battery Voltage) all day long. THe reason for the ballast resistor or resistive wire was to save the points from rapid deterioration. THe Pertronix module is built to run on 12 volts and their coil is also, which is part of the reason the flamethrower has a higher output. I think there has to be some other reason for the coil breakdown or over heating. Even stock coils are run at 12 volts during startup granted it is normally a short duration. Maybe someone else as an idea.
Phil

**Bill M.** · December 30, 2011, 10:19 AM

Re: Coil Overheating

Originally posted by Philip Porter (53007)

Larry, In thinking this over the coils are made to run at 12volts(battery Voltage) all day long. THe reason for the ballast resistor or resistive wire was to save the points from rapid deterioration. Phil

Maybe not. Even dual-point distributors use a ballast resistor.

I had my ballast resistor die and wired around it to get the car running. The engine started to run rough but when I replaced the ballast resistor, it was back to normal (dual-point distributor).

I'll guess that OE coils are designed to run all day with a resistor, but not at full voltage except for starting.

Coil Overheating

Coil Overheating

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