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Discussion Starter #1
My 65 C-code has AC and a basic Retrosound radio, otherwise no added load on the electrical system, no plans to add any additional load on the electrical system. New AGM battery.

My alternator has D8ZF 40A stamped on the case.

How many amps does the alternator put out at idle?

At idle the lights flicker. I increased the idle speed to compensate. I dont have a tach, so no idea what the idle speed is.

Is this an alternator or wiring problem?

I have a new DC alternator harness that Im getting ready to install, but thought that I may as well replace the alternator while Im at it.

The car was "restored" in 05-ish, so everything is 14-ish years old.

Im also going to put the headlights on relays, I have them, just havent figured how where to hide them yet.

Am I better off upgrading to a 60 or 75 amp alternator, will a higher amperage alternator put out more amps at idle? At idle is the only issue Im having, otherwise the charging system is working properly.
 

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That's probably a 63-ish amp alternator unless it came off a luxury Ford or Mercury. Is the voltage regulator a newer solid-state type? Much more reliable than the old points-style and can be disguised with the original type top. Clean all your ground connections. The headlight relay is a good mod. Hiding them under the battery tray is a great spot.
 

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Could be a bit of both. Old wiring old alternator. Another thing that will help is a solid state regulator. Upgrading the alternator to something more than the 40 won’t hurt either. You can get a 60 amp (or so) version of that alternator relatively inexpensive.....
 

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Discussion Starter #4
I also have a new headlight switch and headlight wiring harness. I bought an electronic VR but the terminals are thinner than on the old VR and the plug will not stay on, so I didnt install it. The plug on the new harness will fit the new VR so those will be swapped together.

I spent this weekend cleaning the engine bay. No oil just 14 years of road grime. So much easier to work when everything is clean.
 

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Discussion Starter #5
More questions:

I have 3 alternators:

New from AZ, 65 amp, has a 2 5/8 diameter pulley

Alternator off my 67, case says Motorcraft, 2 11/16 pulley

Alternator on my 65, case says D8ZA 40A, 2 15/16 pulley

Im going to install the new AZ alternator on my 65, move the 65 alt to the 67 and save the Motorcraft alternator.

Which pulley should go on my 65 C-code 289, and which pulley on my 67 200? Keeping in mind that my Alt light comes on at low rpm in the 65.
 

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"D8ZA 40A" - That's a 1978 Alternator. ...which is fine to run...

Do yourself a BIG FAVOR, If you are upgrading the Alternator in the car, Make sure that you upgrade the Voltage Regulator with one of these... No matter what, You should so it anyway regardless if you still have the old "Points Type" Voltage Regulator in the car.

https://www.npdlink.com/product/voltage-regulator-alternator-electronic-replacement-from-the-oe/100810?backurl=search/products?search_terms=voltage%2Bregulator&top_parent=200001&year=

or..

https://www.rockauto.com/en/parts/motorcraft,GR540B,voltage+regulator,4884

:eek:)

Tony K.
 

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Discussion Starter #7
I bought a Standard Motor Products VR166.
 

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You should already be "Good to Go" then..

:eek:)

Tony K.
 

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Make sure your voltage regulator has a good ground. It needs it for a reference source. Part of the problem is the older alternators don't put out as much at low RPM such as idle as today's alternators but that really isn't too much of a issue. The other part of the equation is due to the resistance of the wiring harness itself. First things first, get your idle speed set correctly. If your car is automatic, idle speed is set with the transmission in gear. Not neutral or park. Put the parking brake on, put chocks on the tires or have someone put the brakes on.
 
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