generator to alternator conversion

[tttuba]

I am sure at sometime here you have touched on this but can someone give me info on how to wire in an alternator to a generator wire harness? I am replacing the harness on my 47 gmc and someone had done the conversion to alternator but their wiring skills severely lacked. They had redone some of the wiring but all in the same color and with twice the wires that they needed. Needless to say I don't trust what they did and want to know how to do it the right way. The harness has 2 wires that went to the generator and then went to the voltage regulator. The regulator is no longer. The alternator is a one wire but willing to upgrade it to a multi-wire one. Please let me know the correct way to do this.

[mr48chev]

This is a three wire setup for an internal regulator alternator.


Here is another page that shows how to reroute the generator/regulator wires to work with an internal regulator alternator

With a one wire setup you just eliminate the wires from the 1 and 2 posts. Actually a one wire alternator will have what looks like a plug over those connectors on the alternator.

[solidaxel]

Originally Posted by mr48chev

This is a three wire setup for an internal regulator alternator.


Here is another page that shows how to reroute the generator/regulator wires to work with an internal regulator alternator

With a one wire setup you just eliminate the wires from the 1 and 2 posts. Actually a one wire alternator will have what looks like a plug over those connectors on the alternator.

Thanks, that is a nice diagram, I'm saving that one!

[MrTucker]

Brother's and I think Classic Trucks sells a harness for this. Plug and Play..

[tttuba]

OK so if I have the Amp meter and no charge light can the main wire from the alternator go through the meter to the battery or does it have to be a direct link to the battery? And thanks for the help so far. Love the diagrams.

[NEWFISHER]

I am in the middle of the Gen to Alt conversion and I am also using a 3 wire GM alternator. Here is a good write up that Ray did that I though I would cross contaminate the confusion
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First, you will need an alternator. It should be an SI type which was used on GM cars and trucks from the mid 70s to mid 80s. This type can be identified by having a plug-in connector with two flat blade terminals marked 1 and 2. If available, also get the matching plastic connector, which will probably have two short wires attached to it.

Next, get a small lamp socket suitable for an instrument panel bulb. The only requirement is that it must have two leads or terminals, and they must both be insulated from the socket mounting. This one from Radio Shack will work if you can't find anything else.
http://www.radioshack.com/product/in...ductId=2062366
Also get a 12-14V bulb that fits the lampholder, similar to this one.
http://www.radioshack.com/product/in...ductId=2102801

At this point, disconnect either one of the the battery cables and mount the alternator on the engine, but don't connect any wires to it yet.

The 3 terminals on the regulator should be marked BAT, ARM (or GEN), and FIELD (or FLD). Connect the BAT and ARM (or GEN) wires together with a small screw and nut, and tape up the connection so it can't short out against anything.

Get a length of 18 ga wire long enough to reach from the regulator to inside the cab near the ignition switch and connect one end to the FIELD wire. Tape that connection too. Connect the other end to one terminal of the lamp socket. Connect the other socket terminal to the IGN terminal of the ignition switch or to any other point where the power turns on and off with the switch. Mount the socket where it will be out of the way and the terminals won't short against anything

Now go to where the generator was, or where the alternator will be, and you should see two wires. These will be the other ends of the ARM (or GEN) and FIELD wires you saw at the regulator. Connect the ARM wire to the BAT stud on the alternator. Connect the FIELD wire to the #1 plug terminal and run a short jumper from the #2 terminal to the BAT stud. This completes the wiring.

Reconnect the battery cable. If you get a spark when the cable touches the battery post, disconnect it immediately and look for a wiring error or a wire shorted to ground.

If the wiring checks out ok, turn on the ignition switch, but don't start the engine. The bulb you installed should light, which indicates that the alternator is probably wired correctly. Now start the engine, and the light should go out, which means that the alternator is charging. You should also show a charge on the ammeter if it is wired correctly.

Ray

[NEWFISHER]

I'm going with the one above, If you see smoke in Oregon tonight, it's not a wild fire....it's a 50 Chevy truck burning to the ground!

I'm also installing the 12v to 6v reducers on the coolant gauge and fuel gauge. I wish i was a smaller human with tiny arms.

[G&R's57GMC]

Running through the Ammeter to the Bat from the Alternator is OK IF the Alternator is a low output 37 amp unit.

BUT if the Alternator puts out more then that say 50 or 60 Amps the Ammeter will be short lived.

Its best to run a 10 gauge wire from the Alternator to the Battery ( or junction block or starter ).

To monitor charging install a volt meter that is switched on with the key. This will prevent a minor draw on the battery when the vehicle is not used.

BTW if you use a 1 wire Alternator you will have to goose the engine to get it to start charging.

[NEWFISHER]

Hey Glen!

I used 8 gauge from the alt to batt and then from batt to starter ( fusable link here ) and the alternator is a 24 amp'er so I think I'm good? I also repurposed the GEN wire which looks like 10g from the Regulator harness to the ALT stud.

I have been repurposing most of the cloth wire as its in excellent condition and perfect length for this conversion. I even used the 6v coil wire to power up the HEI relay above the starter on the passenger firewall.

I dropped a wire from the I terminal on the 2 position key switch ( but has 3 outputs...B attery....I gnition....A ccesory) and jumped it through a push button hidden under the dash for starter engagement.

ps the choke came today in a usps envelope? I owe you In and Out again!

[xaircav]

Mad Electric sells a harness and it comes with a very informative book about auto electrics. Lose the ammeter and/or warning light and use a volt gauge and the process is simpler. I put a 63 amp alternator from a mid 70's truck on the 283 in my '53.

[NEWFISHER]

Originally Posted by xaircav

Mad Electric sells a harness and it comes with a very informative book about auto electrics. Lose the ammeter and/or warning light and use a volt gauge and the process is simpler. I put a 63 amp alternator from a mid 70's truck on the 283 in my '53.

Wanting the look of the original gauges.

[mr48chev]

A bigger problem with ammeters is that a lot of us have added equipment that increase the load on the electrical systems to where even the best of ammeters won't handle the load.

With a rig with no electrical powered accessories and all the alternator does is charge the battery and help the lights stay bright when idling along in slow traffic the ammeter isn't taxed noticeably Add halogen headlights, AC, a sound system and electric seats and all the sudden you are drawing some serious amps that all flow through the ammeter if there are no relays allowing the big amp draws to bypass the ammeter.

Still an ammeter only tells you which way the electrical current is flowing be it towards or away from the battery. it doesn't tell anything about how much charge the battery has or how many volts the alternator or generator is putting out.

[_Ogre]

i am a 1 wire alternator fan and have used them on various vehicles for 20 yrs. love them.

running big power loads thru a stock ammeter/wires is asking for trouble.
i had the harness on truk let the smoke out of the ammeter wires 20 some years ago
i was able to stay the fire by reaching under the dash, grab the hottest wire and pull hard
imagine a red hot wire with melted plastic cutting/burning to the bone, all four fingers
it wasn't a pretty sight

i converted my ammeter to a volt gauge with stock appearance
the needle is centered at 12v, my volt gauge is currently reading zero volts, not max discharge

[eagleuh1]

1 wire alternator here 2 on my 50 GMC with 270. I think I ran an 8 gauge wire to the starter battery positive peg from alternator. 65 amp autozone piece. Works great, no charging problems. Just taped up the ends on gen to regulator wires and tied up, incase I wanted to go back. Good luck. Jim

[Highsider]

Originally Posted by NEWFISHER

I wish i was a smaller human with tiny arms.

While are wishing, I wish i knew where the dropped hardware ends up, when it doesn't reach my shop floor.

[NEWFISHER]

Originally Posted by Highsider

While are wishing, I wish i knew where the dropped hardware ends up, when it doesn't reach my shop floor.

I find it at the end of each year next to the single missing socks