OK, help.

Bought an 87 F350 last summer, truck is in OK mechanical shape, but there are areas that I want to improve reliability, etc. where I can, one of which is the charging system.

There are two systems in vehicles I will generally run screaming from--brakes and major electrical, mostly because both are systems that will allow you to put yourself in a dangerous situation without warning you ahead of time, so to speak, so I tend to leave well enough alone on those. However, I've pulled and replaced alternators in the past, so I felt confident enough to man up, buy a new one...

...and then pay somebody else to put it in.

However, I even failed that part. Went to Summit, picked out a 100-amp Powermaster that spec'd out as being compatible with the 460 in the truck, and bought it. Proudly gave it to the guy that was rebuilding my carb (which went phenomenally, if you're north of LA and need a carb done, Pacific Carbs in Ventura), along with a starter, and let him have at it.

Got a phone call about a week later, carb's done, starter's in, alternator won't work. It's a one-wire (which I just figured made it even simpler), and the truck's a 3 wire. Carb guy let me know that he could install it, but that I'd lose the dash gauge (which I would rather keep), and could potentially start a fire (which I don't want at all).

Lots of internet research has mixed results--yes, a one-wire can work. The Powermaster instructions for the model (#57101) mention tying the green/red wire to tab 1 of the alternator to power the idiot light, but nothing about powering the voltmeter. I found a couple of conversion kits (one fairly comprehensive-looking kit at Summit, bunch of generic wiring-in-a-can ones on Ebay), but I don't know if it's actually possible to wire this alternator in such a way that it will power the dash voltmeter. Before I sink even more money into trying to make this one work, would appreciate if anybody ACTUALLY knows if it's possible to install a one-wire alternator on a 460 engine and retain the dash gauge function, without also resulting in a truck-b-que.

As always, any answers, whether correct, entertaining, or both, are deeply appreciated.

 

Pretty sure the volt meter will work regardless. It just needs + battery and ground connections. I suggest wiring the idiot light in.

As an aside you can also upgrade to a 3G alternator. There are several threads on here about it. Below is a link someone with a '92 F250 asked about; it uses the same 2G alternator that your '87 came with. If you decide to go 3G you can make your own wiring harness, or buy a prebuilt one. I'll include a link to one of those too. It's a really simple upgrade with the added benefit of being available at any parts store.

https://www.ford-trucks.com/forums/1...r-upgrade.html
https://www.paperformance.com/3g-conversion-462802a/

 

Get a 130 amp 3G Alternator. You'll also need the wiring harness that slips into the alternator. Other than that, it's very easy to do, and even easier for your carburetor guy to do.

 

Idiot light needs no power on the alternator side - it gets power from the dash, sends it to the alternator to get it excited and start charging, and if no charging happens the alternator effectively grounds the light this making it light up. If the green wire is connected to the big charging cable of the alt you'll be backfeeding battery voltage to the green/red circuit all the time, which is probably not a great idea.

With the 1-wire alternator you should be able to just connect it to the battery, while taping all other wires off. Charge light on the dash won't work, but the voltmeter should still be just fine.

I'd do the 3G upgrade tho.

 

Thanks, all. OK, will put the 1-wire back on the shelf for another day and switch over to the 3G upgrade. Will post back with notes when completed.

 

Sell the 1-wire to someone building a hotrod. You get money back and they get what they need.

Or just install the 1-wire and call it good?