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post #21 of (permalink) Old Sep 12th, 19, 12:39 AM
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Re: 1962 Impala Wiring Question

Originally Posted by Daron Craig View Post
Hey guys,

I have been helping my brother in law with his impala. It has a 350 non-original and a th350 trans. HEI distributor. The alternator has a 1 stud and a plug with 2 wires coming out of it. We are in the process of sorting out the original harness, but I was wondering if any of you guys had a simple diagram of how we can wire it to test fire it? Also, a simple wiring diagram of how the alternator, starter, and distributor need to be wired for final wiring. Thanks guys.
Was the Impala V8 or V6 originally?

There should be a thick wire running from the rear charging post of the alt. Where is that Wire currently running to? Does it go to the POSITIVE BATTERY TERMINAL POST CONNECTOR?

The way it is hooked up now will work and charge the battery. The problem is that the field wire (#1 on the alt) needs to be switched off by the ignition or accessory circuit or the field and regulator will remain energized with the engine off and the key off. This will be draining the battery anytime the engine is not charging. It has about a 4 amp draw so it won't take long to drain the battery.

You can clean up and simplify the wiring and make it work. If you want the gen light to function, we'll need to know first if the car has one or an amp gauge. Then we'll need to know what wiring still exists from the light to where the gen and regulator use to be. Get back to that later.

First, buy a new plug for that alt at the auto parts store. It's going to be really costly, about 3 bucks. The wire that goes to the #2 (sense line) terminal can simply be connected to the large alt output terminal with a crimp connector to the back of the alternator.

The number 1 wire can be connected in many ways but must be switched off when the ignition is off or you'll get that battery drain. This wire is the exciter wire and only needs to supply voltage to get the alt to start charging. Once it starts charging, it no longer needs power to that line. The alt produces its own and you'll see 12 volts to that line once the alt is charging.

It's entirely possible that you don't need to hook up this wire to get a charge out of the alt. Residual magnetism may allow the alt to start charging on its own without the wire. Sometimes you need to kick up the throttle to about 2000 rpm give or take and the alt will start charging. Some guys hook up a momentary switch to apply power. To me, all these methods are for Disney and Mickey Mouse.

The preferred method is to hook that #1 wire to the ignition switch through the indicator bulb or a 5 amp 50volt diode with the silver stripe of the diode facing the alt. The diode or lamp stop power from back feeding the ignition which would cause the engine to keep running when the key is turned to the off position. If using the bulb, if it burns out the alt will not start charging. So as a backup, we run a resistor in parallel to the lamp so if the lamp does burn out, the alt will still start charging.

You can buy the wire with the resistor pre installed from various sources.
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