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Discussion Starter · #1 ·
Hey hey all. So I had posted my heater fan was not blowing in a diff thread a few weeks ago. So I decided to take my dash apart and do a mini resto since I needed to fix a bunch of wiring anyways. Just an update after tracing the orange heater fan wire from heater controls to the heater fan inside the right fender engine side, I saw the connector plug had fallen off!! So I reconnected it back and voila, it worked!! Haha so thanks for that help.

I have my entire dash disassembled and am removing aftermarket gauges and rewiring factory harness to get the original water temp, oil press, and battery gauges working again. Problem is, is I have a Mark Jones 467 engine with a higher output internally regulated alternator (original external reg is jumpered ad bypassed). I can start the engine right now and I have 14v on both connectors in the 2-pronged battery gauge factory plug that connects to the gauge. I have the understanding that the gauge is supposed to "sense" the voltage difference between the battery voltage and the alternator output which should be around 2-3.6v. So not sure I can get it to work since I have an updated alternator?!?!

I've read a lot on how to run new wires to the horn relay and the battery junction in front of battery, but It's not that big a deal. Just wondering if any of you have a different thought on what I can do. I am not going to run new wires so if the original harness won't work, I'm fine with that since I'd rather have the 200amp alternator than a working gauge haha. I have never had voltage or amp issues with my car so not too concerned with not knowing voltage output these days.

New dash is coming along very nicely. I even had to drill a new hole in my 467 motor to tap the hole for the original oil press sending unit haha. Good times with the motor in the car haha. I'll try to post pics asap. I even have the courtesy lights and glove box light working again!!

Thanks for any constructive input :)
 

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You will not be able to use the factory style ammeter with anything other then the bone-stock alternator and wiring system.

To put it in the most simple terms, the factory "charge-discharge" gauge is a voltmeter that reads the voltage across the #10 gauge charging wire across the radiator support and is "calibrated" to function with that and an alternator with no more than 63 amps approx. of rated output.

When you go changing things, (which should be upgrading wiring anyway with a 200 amp alternator), the system no longer has the inherent factory designed voltage drop specs to run the gauge properly.
 

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You will not be able to use the factory style ammeter with anything other then the bone-stock alternator and wiring system.

To put it in the most simple terms, the factory "charge-discharge" gauge is a voltmeter that reads the voltage across the #10 gauge charging wire across the radiator support and is "calibrated" to function with that and an alternator with no more than 63 amps approx. of rated output.

When you go changing things, (which should be upgrading wiring anyway with a 200 amp alternator), the system no longer has the inherent factory designed voltage drop specs to run the gauge properly.

Joe and All,
Just thinking about this - the high out-put two wire alternator. If the #10 red wire is retained from the battery positive terminal block to the horn relay the existing ammeter that reads the voltage drop across this wire should continue to work. Albeit with a maximum of 60 ish amps flowing as current greater than this will 'peg' the ammeter. As the alternator is there to carry connected loads and if the loads he is adding require more than 60 amps then yes he needs to rewire his electrical system.


My 60 amp alternator works fine but my loads are pretty small. How many amps are needed to support; FI, electrical fuel pumps and fans, oh and a stereo amp in addition to the normal loads? Newer cars have alternators with greater than 100A out-put to support these loads and have gone to a voltmeter rather than an ammeter. Ideally one should have both a voltmeter and ammeter and the ammeter reading current into and out of the battery and the output of the alternator.
Al
 

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Discussion Starter · #5 ·
You will not be able to use the factory style ammeter with anything other then the bone-stock alternator and wiring system.

To put it in the most simple terms, the factory "charge-discharge" gauge is a voltmeter that reads the voltage across the #10 gauge charging wire across the radiator support and is "calibrated" to function with that and an alternator with no more than 63 amps approx. of rated output.

When you go changing things, (which should be upgrading wiring anyway with a 200 amp alternator), the system no longer has the inherent factory designed voltage drop specs to run the gauge properly.

Joe and All,
Just thinking about this - the high out-put two wire alternator. If the #10 red wire is retained from the battery positive terminal block to the horn relay the existing ammeter that reads the voltage drop across this wire should continue to work. Albeit with a maximum of 60 ish amps flowing as current greater than this will 'peg' the ammeter. As the alternator is there to carry connected loads and if the loads he is adding require more than 60 amps then yes he needs to rewire his electrical system.


My 60 amp alternator works fine but my loads are pretty small. How many amps are needed to support; FI, electrical fuel pumps and fans, oh and a stereo amp in addition to the normal loads? Newer cars have alternators with greater than 100A out-put to support these loads and have gone to a voltmeter rather than an ammeter. Ideally one should have both a voltmeter and ammeter and the ammeter reading current into and out of the battery and the output of the alternator.
Al
Thanks for the confirmation. Yea the meter is pegging at C so I'm sure with my upgraded alternator plus msd ignition reqs, I'm gonna call it OK as long as I see the needle not showing a dead battery haha. Oil pressure also reads to H but water temp is working nicely haha. I had a bunch of fun rewiring the dash and removing all aftermarket stuff Haha. Looks so much cleaner. I'll post pics soon.
 
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