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Discussion Starter · #1 ·
My Relay should arrive tonight, Hoping to solve my 5. 1 V at coil in run position (engine off) , 10.1 V at idle at coil. I already have questions.
1. Where the small purple relay line is attached to the Ig. wire /Resistance wire ( red/green ) on a 70. The black dot in diagram. The red /green wire was removed from the (+) side of the coil. Do I reconnect it to the Positive side? I would then have small purple, orange relay wire, Red-green Ig. wire, and Red pertronix 1 wire all attached to the (+) coil terminal OR
2. Orange relay, and Red Pertonix wire to (+) coil terminal. Then the Purple and Red-green Ig wire are attached together separately.
If it matters, the vehicle is a factory tach vehicle. with a flamethrower 1.5 Ohm (checked good).

Thanks in advance.
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I hate these worthless diagrams that don't show you what is happening inside the relay. Its easy enough to figure it out, but its so silly not to show what is happening.
You have a Pertronix and you want to increase the voltage to 12v at the coil?

Stop over thinking this. Connect it exactly as shown with only the orange wire on the coil + terminal. If you connect all that stuff together as you suggest nothing will work and may cause a short that would damage something.
You have a 70, so wire 904 Green with Red Stripe is the wire that the small purple should connect to. You will find it at the voltage regulator. Connect a wire there and run it to the new relay.
Don't connect any extra wires- only whats shown, except the Pertronix which connects to the coil negative, and the high voltage wire out the top of the coil.
 

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Discussion Starter · #3 ·
I hate these worthless diagrams that don't show you what is happening inside the relay. Its easy enough to figure it out, but its so silly not to show what is happening.
You have a Pertronix and you want to increase the voltage to 12v at the coil?

Stop over thinking this. Connect it exactly as shown with only the orange wire on the coil + terminal. If you connect all that stuff together as you suggest nothing will work and may cause a short that would damage something.
You have a 70, so wire 904 Green with Red Stripe is the wire that the small purple should connect to. You will find it at the voltage regulator. Connect a wire there and run it to the new relay.
Don't connect any extra wires- only whats shown, except the Pertronix which connects to the coil negative, and the high voltage wire out the top of the coil.
I must overthink things,:) I'm an engineer. Just not an EE. Pertronix goes from (+) coil terminal (red wire ) to (-) coil term. (Black wire).
Thanks for clearing it up.
 

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FYI - your tach will no longer work with the relay in place, since it depends on the coil power pulses to create a reading.

You can bypass the resistor wire by feeding the coil directly from the tach connector. Pertronix will receive 12V, tach will still work.
 

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Discussion Starter · #5 ·
FYI - your tach will no longer work with the relay in place, since it depends on the coil power pulses to create a reading.

You can bypass the resistor wire by feeding the coil directly from the tach connector. Pertronix will receive 12V, tach will still work.
Ok, that sucks..... Why wouldn't Pertronix acknowledge that? When you say tach connecter, do you mean 2 pin connector behind cluster?
 

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The "simple" solution? Leave everything connected just as if you had a points distributor. Resistance wire in place, RED/GREEN to the Coil+. Distributor lead to the Coil-. NOW, connect your relay as follows:
1. Large RED wire to your 12vDC source. The "common" side of the Starter Solenoid is a good place, with the relay mounted below it.
2. BLACK wire to ground.... the mounting screw for your relay will suffice.
3. Small PURPLE wire to Starter Solenoid "I" post. Use a small ring terminal under the "BROWN" bypass wire connection.
4. ORANGE wire to Pertronix Ignitor RED wire.

Your tach should function normally.

FWIW, your voltage measurement at the Coil+ will only be accurate if the coil primary circuit is grounded; otherwise it will reflect the fact that the circuit is constantly switching between open and closed (dwell).
 

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Discussion Starter · #8 ·
I also have a '70. The pink resistor wire is very short and located at the steering column. I removed that pink wire and replaced it with a wire of thicker gauge. I now have 14 volts at the coil when the key is turned on.
Does your tach still work? Would you be supplying 14V to the tach?
 

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Discussion Starter · #10 ·
The "simple" solution? Leave everything connected just as if you had a points distributor. Resistance wire in place, RED/GREEN to the Coil+. Distributor lead to the Coil-. NOW, connect your relay as follows:
1. Large RED wire to your 12vDC source. The "common" side of the Starter Solenoid is a good place, with the relay mounted below it.
2. BLACK wire to ground.... the mounting screw for your relay will suffice.
3. Small PURPLE wire to Starter Solenoid "I" post. Use a small ring terminal under the "BROWN" bypass wire connection.
4. ORANGE wire to Pertronix Ignitor RED wire.

Your tach should function normally.

FWIW, your voltage measurement at the Coil+ will only be accurate if the coil primary circuit is grounded; otherwise, it will reflect the fact that the circuit is constantly switching between open and closed (dwell).
Well partial success.
Wired as described above.
When first fired started up but would not stop when key turned to off. Removed brown wire from I on the solenoid and it then functioned property. (run/off)
Still only 5.5 volts in run position Coil - Grounded and voltmeter between + coil and good ground. Key on
Tried wiring Preonix diagram (purple to red/green wire. No tach due to no pulse. still only 5+ volts
Checked pertonix ground .2 ohms.
Any other thoughts? I am hoping bad coil. but it checks out for primary and secondary windings. (see above for #)
 

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Well partial success.
Wired as described above.
When first fired started up but would not stop when key turned to off. Removed brown wire from I on the solenoid and it then functioned property. (run/off)
Still only 5.5 volts in run position Coil - Grounded and voltmeter between + coil and good ground. Key on
Tried wiring Preonix diagram (purple to red/green wire. No tach due to no pulse. still only 5+ volts
Checked pertonix ground .2 ohms.
Any other thoughts? I am hoping bad coil. but it checks out for primary and secondary windings. (see above for #)
Well, it sounds like one issue you have is something backfeeding the ignition system when you turn the key "off", since removing the BROWN wire, which is connected directly to the coil feed (RED/GRN) at the firewall connector stops it. Do you have an alternator conversion of some kind?

Second issue is your "voltage check" at the coil+ which is STILL not how you check the supply voltage to the coil. A closed circuit is going to reflect the TOTAL resistance in the circuit whether it's "upstream" or "downstream" of where you connect the meter lead. That "5.5 volts" reflects the resistance of the resistance wire, the coil primary, the Ignitor, all the wiring and connections from the ignition switch all the way to ground. VOLTAGE DROP is the correct method. a) Check the voltage at the battery and make a note. Let's assume it's 12.5 volts. b) Turn the ignition to the "ON" position. c) Put the BLACK lead on the battery positive post and the RED lead on the Coil+. Note the reading. Let's assume it's 6.6 volts (which is approximately what it should be). d) Subtract 6.6 from 12.5.... using "old math" I get 5.9 volts. If your charging system is putting out 14.2 volts then when the engine is running your supply at the coil will be 7.6 volts (14.2 - 6.6). The voltage drop will not change regardless of whether the engine is running, or not.
 

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Discussion Starter · #12 ·
Well, it sounds like one issue you have is something backfeeding the ignition system when you turn the key "off", since removing the BROWN wire, which is connected directly to the coil feed (RED/GRN) at the firewall connector stops it. Do you have an alternator conversion of some kind?

Second issue is your "voltage check" at the coil+ which is STILL not how you check the supply voltage to the coil. A closed circuit is going to reflect the TOTAL resistance in the circuit whether it's "upstream" or "downstream" of where you connect the meter lead. That "5.5 volts" reflects the resistance of the resistance wire, the coil primary, the Ignitor, all the wiring and connections from the ignition switch all the way to ground. VOLTAGE DROP is the correct method. a) Check the voltage at the battery and make a note. Let's assume it's 12.5 volts. b) Turn the ignition to the "ON" position. c) Put the BLACK lead on the battery positive post and the RED lead on the Coil+. Note the reading. Let's assume it's 6.6 volts (which is approximately what it should be). d) Subtract 6.6 from 12.5.... using "old math" I get 5.9 volts. If your charging system is putting out 14.2 volts then when the engine is running your supply at the coil will be 7.6 volts (14.2 - 6.6). The voltage drop will not change regardless of whether the engine is running, or not.
Thanks for the help Bart

Voltage across battery key off 12.6V
Voltage key on Black to bat +, Red to coil + 6.40 V
Same measurement engine running 3.90 V (brown wire removed from "I" terminal)
Same measurement key on engine not running .15 V (brown wire connected "I" terminal)
 

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Thanks for the help Bart

Voltage across battery key off 12.6V
Voltage key on Black to bat +, Red to coil + 6.40 V
Same measurement engine running 3.90 V (brown wire removed from "I" terminal)
Same measurement key on engine not running .15 V (brown wire connected "I" terminal)
Voltage to coil is fine. Removing or reconnecting BROWN wire at "I" terminal should have ZERO effect on voltage drop test unless starter solenoid has internal short across feed and "I" terminals.
 

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Discussion Starter · #14 ·
Voltage to coil is fine. Removing or reconnecting BROWN wire at "I" terminal should have ZERO effect on voltage drop test unless starter solenoid has internal short across feed and "I" terminals.
Isn't the point of installing the relay to get 12 V to the coil and pertonix 1?
 

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The point is to get 12V to the Pertronix as it is a solid-state electrical component designed to operate on 12v. You still want your factory tachometer to work, right? Also, if you have an oil-filled, canister-type coil with 1.5 ohm primary winding (stock or stock replacement type) you want the reduced voltage in place to avoid overheating the coil, especially with the increased dwell provided by the Pertronix Ignitor. FWIW, increasing the spark voltage on a "street" engine typically does nothing more than drain your wallet.
 

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Discussion Starter · #16 ·
The point is to get 12V to the Pertronix as it is a solid-state electrical component designed to operate on 12v. You still want your factory tachometer to work, right? Also, if you have an oil-filled, canister-type coil with 1.5 ohm primary winding (stock or stock replacement type) you want the reduced voltage in place to avoid overheating the coil, especially with the increased dwell provided by the Pertronix Ignitor. FWIW, increasing the spark voltage on a "street" engine typically does nothing more than drain your wallet.
I I am not getting 12 volts to the coil, how do I get 12 volts to the pertonix 1? Coil is a 1.5 ohm flamethrower, oil bath. I had approx the same voltage running no relay. I was hoping to get 12 volts to pertonix to solve miss issue. that developed within las 300 miles or so. The engine is not nearly stock. 11.0 comp. roller cam roller rockers. wire, cap rotor new. pertonix and coil 10 years old but low mikes
 

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Discussion Starter · #18 ·
You get 12v to the Pertronix by connecting its RED wire to the relay's ORANGE wire.
Any idea why the engine continues to run when brown wire is connected to "I" and the system functions properly when removed from the terminal. Vehicle shuts down when key is off and the brown plug is pulled.
Thanks again.
 

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Any idea why the engine continues to run when brown wire is connected to "I" and the system functions properly when removed from the terminal. Vehicle shuts down when key is off and the brown plug is pulled.
Thanks again.
Sounds like the starter solenoid is internally shorted between battery and bypass ("I" post).
 

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Woodchuck's directions are correct, but the starter solenoid may be defective. Set your meter to read voltage, remove all wires from solenoid "I", connect one voltmeter lead to chassis and the other to "I". If you get any voltage, the solenoid is defective.
After resolving this, then double check your connections: relay black to chassis, relay purple to brown wire and solenoid "I", Igniter red (in distributor) to orange on relay, and relay red to battery +.
As Woodchuck pointed out, you are supposed to have reduced voltage at the coil after starting, but his directions should give you 12v at the Pertronix1 inside the distributor, and your tach should still work.
If the solenoid isn't the problem, then here is a long shot: the Pertronix1 needs the distributor ground wire to be connected- one end to the body of the distributor on the left and the other end to the plate where the arrow is. Disregard where the screwdriver is pointing. Floating grounds can cause havoc, so it's worth checking.
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