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1965 A code 289 with stock everything , complete new OEM type wiring harness, new points , condenser, cap & rotor and coil ( "correct "replacement type ) . With the key on not running coil + is 6.37 V , with the car running it starts at 9.2ish and continues to go up as long as I hold the meter on it ( its been as high as 11.5 V ) . The pink resistance wire value is a bit low @ 1.2 ohms . Voltage will stay around 9.3 if I disconnect the alternator , voltage will also climb with the brown wire removed from solenoid . Its burnt a new set of points within a 25 mile drive and I'm sure it'll do it again if it stays this way . Any ideas ?? Thanks
 

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I would suggest that you purchase a set of Echlin points and condenser (available from NAPA Auto parts stores) . Poor condenser quality is likely the culprit, not the voltage you are reading. That said, the resistor wire is available from the usual Mustang vendors if you suspect it is contributing to the issue.

Z.
 

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Voltage will climb with the engine running as the alternator has to produce greater voltage then the battery in order to charge. This extra voltage will effect everything. The 1.2 ohm is fine, thatt about the impeadence of the coil. Both will have about the same voltage drop roughly. Going up to over 11 volts has me worried you has a issue with your voltage regulator.

As far as your points. Probably a bad condenser. What I think most people aren't aware of the coil has a primary and secondary windings. When the points open, that's when the spark is made. It's the magnetic field collapsing. Not only does this cause a high voltage secondary spark to the plugs but it also causes a high voltage primary spark very much like at the plugs. Obviously you don't want a spark in the kilovolt range going back into the system as it's destructive. This is the purpose of the condenser to absorb this spark. And yes, even the little coil in a relay acts like a ignition coil making a spark.
 

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Discussion Starter #4
I have Standard Ignition points and condenser , 2 bad condensers ?? plus the first one I replaced ? Seems unlikely but maybe.
Regulator could be a problem , I've seen 15.1 volts at the battery at idle
 

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The 15.1 alternator output is probably close to the maximum recharge rate. If you battery is low or you have dirty cable connections, this isn't beyond specs (as along as it drops as the battery charge comes up.
 

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Ill test the battery as it is from 2014 , cables are new along with all the wiring . Battery is fully charged 12.7 (with charger) but it could be bad , just put the meter on it again varies between 15.1-15.5 at idle . Seems like too much since the battery is charged
 

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Discussion Starter #7
Battery is bad , also going to get a new voltage regulator tomorrow . Ill test it all again when the new parts are in .
Thanks for the help .
 

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Ill test the battery as it is from 2014 , cables are new along with all the wiring . Battery is fully charged 12.7 (with charger) but it could be bad , just put the meter on it again varies between 15.1-15.5 at idle . Seems like too much since the battery is charged
there is a heavy draw on even a fully charged battery when it’s turning the motor over. It takes a few minutes for the alternator to “catch up”. As pointed out, the battery voltage at idle should drop after a bit. A solid state regulator is your best bet A regulator from an ‘80’s Mustang will be the solid state variety and even fit under the stock regulator cover if a stock look is desired.

I have Standard Ignition points and condenser , 2 bad condensers ?? plus the first one I replaced ? Seems unlikely but maybe.
Regulator could be a problem , I've seen 15.1 volts at the battery at idle
if the condensers tried were both of the same make, then two failures would not be unusual. As stated, condenser quality has become very spotty since new cars don’t use them anymore . Generally speaking , aftermarket parts manufacturers don’t care about quality if there are no customers with deep pockets anymore .
 

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Also check your coil. With the engine running and your voltmeter connected to the coil+ (red) and ground (black) the voltage is going to reflect the TOTAL resistance in the circuit, including the resistance wire, wiring and connectors, coil primary circuit, resistance across the points, etc. As the coil gets hot it could be breaking down (check resistance in the coil primary cold, then hot and compare) or, since you're looking at an "average" voltage as the points open & close (dwell) an increasing voltage could be a sign of a bad condenser.

Anyhow, series voltage DROP is a much better method of testing resistance than a parallel voltmeter test.
 

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Discussion Starter #10
New voltage regulator keeps voltage at around 14.5 , before on high idle the volts were as high as 16.2 . Voltage is steady on the + side of the coil now but its still around 10.7 , is that ok for the points ? Most of everything I build has electronic or its distributorless ignition I don't usually work with points , I usually get rid of them but this customer wants to keep everything as is .
 

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New voltage regulator keeps voltage at around 14.5 , before on high idle the volts were as high as 16.2 . Voltage is steady on the + side of the coil now but its still around 10.7 , is that ok for the points ? Most of everything I build has electronic or its distributorless ignition I don't usually work with points , I usually get rid of them but this customer wants to keep everything as is .
when the points and condenser are doing a proper job, points should last 7,500 miles before needing any adjustment. And a lot farther than that between replacements.
I know the cars my parents had in the 1960’s (all Fords) went farther than 7,500 miles between adjustments ( a lot farther, they were penny pinchers), and the cars ran great the whole time.

Z
 

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Discussion Starter #12
when the points and condenser are doing a proper job, points should last 7,500 miles before needing any adjustment. And a lot farther than that between replacements.
I know the cars my parents had in the 1960’s (all Fords) went farther than 7,500 miles between adjustments ( a lot farther, they were penny pinchers), and the cars ran great the whole time.

Z
I understand points will last thousands of miles when working properly . What I meant was is the 10.7 volts OK for the points since I read the Ford points ignition system is supposed to run on less than that .
 

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I understand points will last thousands of miles when working properly . What I meant was is the 10.7 volts OK for the points since I read the Ford points ignition system is supposed to run on less than that .
How are you measuring the voltage at the coil? Points open, closed, just key on?
 

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The voltage may be on the borderline, I really don’t know what is the maximum safe number, (sorry). And essentially the stock coil is really a 6 volt piece. Is it getting hot to the touch ? i.e. more than just warm ?

Z
 

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How are you measuring the voltage at the coil? Points open, closed, just key on?
The 10.7V is with the car running pos lead from the meter on the + of coil and neg lead on battery negative .
If I put the test leads from the meter on the coil it reads about 4.7 V
 

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The 10.7V is with the car running pos lead from the meter on the + of coil and neg lead on battery negative .
If I put the test leads from the meter on the coil it reads about 4.7 V
The 10.7V you are seeing is an average of the voltage in the circuit based on the amount of time the points are closed, when you'll see actual circuit voltage, and when the points are open, when you'll see battery voltage. With a DMM you can't see "resisted voltage" in an open circuit. A more definitive test would be to check the voltage drop between the battery+ and coil+ with the engine off, key on and points closed, or shorted to ground, and subtract from battery voltage.
 

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I don’t recall that type of test being suggested anywhere in the Ford published shop manual. I could’ve missed it though. I don’t know if those type of measurements are revealing anything useful . Might just be a red herring that is leading you down the proverbial rabbit hole. If you stick with the ignition and charging tests outlined in the Ford shop manual, then you will have a methodical path that takes you from A to B to C, all the way to “Z”.
One thing to always check is the ground from the engine to firewall. And the grounding strap inside the distributor, (not applicable on dual point distributors). A bad ground around the engine WILL drive you crazy. As will battery cables corroded inside the insulation. I know you mentioned that the cables and wiring are new. Still, it’s a good idea to hook up the multimeter on ohms at each end of a wire then do some wiggling all along the run of the wire or cable. These days a new part doesn’t guarantee that it’s a good part.

best of luck tracking this issue down

Z
 

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Discussion Starter #18
The voltage may be on the borderline, I really don’t know what is the maximum safe number, (sorry). And essentially the stock coil is really a 6 volt piece. Is it getting hot to the touch ? i.e. more than just warm ?

Z
Its warm but you can keep your hand on it all day , its not hot .
The 10.7V you are seeing is an average of the voltage in the circuit based on the amount of time the points are closed, when you'll see actual circuit voltage, and when the points are open, when you'll see battery voltage. With a DMM you can't see "resisted voltage" in an open circuit. A more definitive test would be to check the voltage drop between the battery+ and coil+ with the engine off, key on and points closed, or shorted to ground, and subtract from battery voltage.
As per your test procedure I come up with 6.22 volts , if this is the correct way to test its just about perfect .
 
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