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1970 Opel Gt - Purchased July 1972 - Chartreuse - restored - 3000 miles as of 02-16, 2021 -
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Discussion Starter · #1 ·
I recently installed a 3 ohm resistor coil and pertronix ignition system and my 70 gt is running better that it ever has, however I have noticed after just 10 or 15 miles that both the coil and voltage regulator are much too hot to touch and worry this will eventually lead to something bad - I also removed the resistor wire and replaced it with a regular wire directly to the coil from the same clip on the fuse box as where the resistor wire came from - I have searched and read everything I can however have found nothing that addresses this specific issue. Any help will be greatly appreciated. Thanks, Will
 

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Detroit,where my home was
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..... I also removed the resistor wire and replaced it with a regular wire directly to the coil from the same clip on the fuse box as where the resistor wire came from....
did it say in the instruction / installation manual to replace the resistor wire? if it didn't put the resistor wire back.
 

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I recently installed a 3 ohm resistor coil and pertronix ignition system and my 70 gt is running better that it ever has, however I have noticed after just 10 or 15 miles that both the coil and voltage regulator are much too hot to touch and worry this will eventually lead to something bad - I also removed the resistor wire and replaced it with a regular wire directly to the coil from the same clip on the fuse box as where the resistor wire came from - I have searched and read everything I can however have found nothing that addresses this specific issue. Any help will be greatly appreciated. Thanks, Will
I recall your postings on the petronix and coil hookup- sounds like you have it correct! The coil will build excessive heat if powered up (key on) without engine running (coil discharging)...it's not good for it, and doesn't take too many minutes to happen. It'll also get to hot if it's actually a 1.5ohm coil.

Use a voltmeter to check voltage on running engine~ have helper hold rpm at about 3000 for a couple minutes while you check battery voltage a few times...and then check it again at idle. Report back - will be looking for high and low voltage statuses.
 

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I recall your postings on the petronix and coil hookup- sounds like you have it correct! The coil will build excessive heat if powered up (key on) without engine running (coil discharging)...it's not good for it, and doesn't take too many minutes to happen. It'll also get to hot if it's actually a 1.5ohm coil.

Use a voltmeter to check voltage on running engine~ have helper hold rpm at about 3000 for a couple minutes while you check battery voltage a few times...and then check it again at idle. Report back - will be looking for high and low voltage statuses.
I think this expands on what you are saying.

If the VR AND the coil are getting too hot, perhaps you are charging high. Is your VR an old school (relay type) or a newer style, solid state, type?

What does your Ammeter usually read while driving with nothing on? It should get to almost dead even after the battery recovers from the draw from starting. If it still appears to be charging (needle reads higher than center by a considerable amount) then you may have a faulty VR.
 

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Discussion Starter · #5 ·
Coil Hot - replace resister wire??

did it say in the instruction / installation manual to replace the resistor wire? if it didn't put the resistor wire back.
Prior to removing the resistor wire I only had around 7.5 volts at the coil....With out the resister wire I am up to around 10.5...is that too much
 

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Discussion Starter · #6 ·
Coil too hot

I think this expands on what you are saying.

If the VR AND the coil are getting too hot, perhaps you are charging high. Is your VR an old school (relay type) or a newer style, solid state, type?

What does your Ammeter usually read while driving with nothing on? It should get to almost dead even after the battery recovers from the draw from starting. If it still appears to be charging (needle reads higher than center by a considerable amount) then you may have a faulty VR.
The Voltage Regulator is the original....Ammeter reads just above center charging which is normal when nothing is on...
 

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Prior to removing the resistor wire I only had around 7.5 volts at the coil....With out the resister wire I am up to around 10.5...is that too much
Without the resistor wire you should have the same voltage as your battery/charging system.
 

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Discussion Starter · #8 ·
I recall your postings on the petronix and coil hookup- sounds like you have it correct! The coil will build excessive heat if powered up (key on) without engine running (coil discharging)...it's not good for it, and doesn't take too many minutes to happen. It'll also get to hot if it's actually a 1.5ohm coil.

Use a voltmeter to check voltage on running engine~ have helper hold rpm at about 3000 for a couple minutes while you check battery voltage a few times...and then check it again at idle. Report back - will be looking for high and low voltage statuses.
Thanks, will get back to you the first week of July when I return home with status....
 

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Detroit,where my home was
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Prior to removing the resistor wire I only had around 7.5 volts at the coil....With out the resister wire I am up to around 10.5...is that too much
the resistor wire is used to keep a lower voltage on the coil. The coil only gets the full voltage when starting the engine, then the resistor wire is as it were shorted.
Try to connect the resistor wire again, just fix it between the new wire you installed and the original spot where the resistor wire was hooked up, and see what happens.
 

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Thanks, will get back to you the first week of July when I return home with status....
I'll be out of town that week, but others here are smarter than me to help you. I think I'd simply have steered you (in this order) towards strong wiring and battery connections, the internal regulator contacts (if overcharging at run) and then the condition of the battery itself. I'll check back when I can.
 

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I recently installed a 3 ohm resistor coil and pertronix ignition system and my 70 gt is running better that it ever has, however I have noticed after just 10 or 15 miles that both the coil and voltage regulator are much too hot to touch and worry this will eventually lead to something bad - I also removed the resistor wire and replaced it with a regular wire directly to the coil from the same clip on the fuse box as where the resistor wire came from - I have searched and read everything I can however have found nothing that addresses this specific issue. Any help will be greatly appreciated. Thanks, Will
Is this one of those knock-off units that's sold on flea bay?
 

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Discussion Starter · #12 ·
Is this one of those knock-off units that's sold on flea bay?
Actually it is a bosh coil and was blessed by pertronics as OK - when I purchased it I was never told to disconnect the resistor wire - was purchased from Opel's unlimited with a clear distributor cap
 

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Actually it is a bosh coil and was blessed by pertronics as OK - when I purchased it I was never told to disconnect the resistor wire - was purchased from Opel's unlimited with a clear distributor cap
Have you tried calling OU and asking them for the technical advice on the parts they sold you?
 

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Actually it is a bosh coil and was blessed by pertronics as OK - when I purchased it I was never told to disconnect the resistor wire - was purchased from Opel's unlimited with a clear distributor cap
Bosch used several different primary resistance coils that "could work" depending on HOW you wired it.

Example 1.2 primary coil with a 1.8 ohm resistor wire

Or 3.0 ohm primary without a resistor wire.

Me, myself and I likes to use a .1 ohm primary field coil.
 

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Discussion Starter · #15 ·
Coil too hot

Hey Dan, do you think that could be my problem - I will check out the ohms again and the voltage at the coil and see what I get - will not be able to do that as am out of town right now. Thanks for your response. Will
 

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Hey Dan, do you think that could be my problem - I will check out the ohms again and the voltage at the coil and see what I get - will not be able to do that as am out of town right now. Thanks for your response. Will
Yep, could be- but likely unrelated to the hot regulator. Of course, check it against what vendor advertised and wire/return it as needed.

I'm curious as to low 10.5volt at coil (same as battery- as wired)...assume here not running...and then what happens during charge/run. Might tell something about: what regulator is/isn't doing about what it's seeing at battery, poor connections and/or general battery condition.
 

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Discussion Starter · #19 ·
You bring up a very good question.

Oil-filled or a E-core?
D\
Dan, based on what I have read the coil is a Bosch coil made in Brazil 022119027 9220081083 are the numbers stamped on the bottom and correspond to an artical I read where a guy did a lot of research and stated this is one of the better coils out there - not sure if it is oil filled or not - can't hear anything when I shake it - when I do an OHM test with the meter set on 200 it gives me a reading of 3.7, consistently.....Based on what I have read on the forum I did remove the original resister wire, which powered the coil, so as not to double up on the resistance, I believe I read that the original wire was 1.8 ohms of resistance....so it seems that with a coil with 3.7 ohms of resistance would be all that is needed...
Could I have a short somewhere - could I have attached a wire incorrectly, I rebuilt this entire car and I am not a mechanic, I repeat, not a mechanic and my weakest abilities would revolve around electrical - another thought - I removed the tach wire from the negative side of the coil as my tach was not working and it seemed to affect the way the care started, or actually the car would not start until I remove it, something I read in the forum, so my only connection to the negative side of the coil is the one wire from the electronic ignition in the distributor.....YOUR THOUGHTS...
I will put the coil back on tomorrow and test voltage in all areas again - battery is new and has been reading over 12 volts and when the car is running it measures 10.75 volts at the coil but again I will double check - the heat issue seems to be the only issue that I have keeping me from driving almost worry free. I have been one of those people that loves to drive my Opel more than working on it but I seem to work on it much more that driving it - and it was a daily driver for me from 1972 until around 1982
 
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