I have a 1958 f100 with a 305 chevy small block in it. The guy I bought the truck from had a mess of wires all over the place. The alternator has 3 wires on the single back post. 1 red going to the positive battery terminal, then 1 red and 1 black wire going to a fuse under the dash. I'm no wiring expert but that doesn't seem right to me. I don't know if it's related but there's a ground wire going from my voltage gauge to my engine block that's melted pretty bad.
Sometimes a secondary wire is run to the fuse block... but I can't explain the details... also do you have an ammeter in the dash?
I would put in a warning light (not an LED). 10g min from battery to rear battery post on alt, #2 off of plug to rear battery post on alt and #1 to charge light. The other side of the light goes to the ign switch (switched power). BTW I'm assuming it's a real 3 wire 10si as 1 wires have a cover over the regulator hole (which could be missing). Your going to need a regulator plug, either a regular one or one with a diode in it.
So are you still using the Ford voltage regulator ? In the photo the internal one is unhooked. If so I would eliminate the trucks regulator and use the one built in the alternator.
The wiring on the alternator could be right, if the alternator has a self-exciting regulator in it. We really have no way of knowing this. As for the volt meter....tell us more about it, post a picture of it. If it's an ammeter, but someone thought it was a volt meter, then wiring one side of it to ground would melt the ground wire. That's why we're asking about it.
It's a newer autometer voltage gauge. From what I can tell there are several grounds on the volt meter ground stud and the one maybe 16 awg wire leaving it to the top of the engine (that's the melted wire). Maybe just to many things sharing a small ground wire that's not making a good connection on the engine block? It seems like they wired a 3 wire alternator as a 1 wire alternator? Which may be working fine, it may be unrelated to the melted wire. Heres the gauge, the melted wire and the grounding point on the engine.
If there are multiple things grounded to the voltmeter and only a single 16 gauge wire grounding all of it that may be a problem, remember the ground Carries the same amperage as the power side.
Thanks for all the input guys. I'm going to pull the gauge cluster and probably do some rewiring. I'm going to add new ground straps to the engine and frame too
I've got several wiring diagrams for alternators here. Photobucket Don't pay attention to the one dated 11 Dec as that is for the newer CS 30. I snagged the one that 1oldtimer posted as it is real clear on doing it with a light. This guy in El Paso sells the plug with the diode built in that 1oldtimer showed. he gives great service and although a tad bulky for some street rodder tastes it simplifies things and saves hunting for a diode if you go that way. CHEVY DELCO ALTERNATOR HARNESS ANTI- FEEDBACK DIODE 10SI 12SI 15SI 27SI WIRE | eBay