Ok, I recently had what I thought was altenator issues, when my voltmeter dropped and the car stalled. Much to my surprise the alt tested out fine, but I did find a wire in the battery box that was connected from the battery to the pos on the altenator was melted & broken in the battery compartment (almost a fire **) What gives? It appears to be a 10 ga wire. Is this correct for a 78, is the posi lead for the altenator supposed to come off the battery??? Seems like a long run!! Also the neg on the altenator goes directly to the battery also.
Can you Guys tell me what is correct for wiring the pos & neg on the alt ??
Help would greatly be appreciated.

 

That wire carries all the current for the car, it runs from the alternator to the battery, the current then runs back up front on the big + cable to the starter where the fuse links are for distribution to the entire car. Makes a lot of sence huh? Replace the burned cable with a #8, #6 if you can or are running fans, halogen and big stereo.

I never liked the way that was done, long way around the barn it seems.
I am replacing my fuse links with breakers and feeding them from the alternator instead of the starter cable. Distributing all power from a term block under the hood since thats where it gets used. Only thing in the back of the car that gets fed like that is the battery and stereo amp.

 

I'll run an 8 gage lead, is it ok to run dual fans off the alt where this posi lead connects??

 

On a 78 the only wires going to the battery box are the 2 main battery cables. Bubba??

 

Then where does the posi lead on the alt go to?? Or supposed to go to??

 

To the starter solenoid terminal where the battery cable connects to protected by a 16 gauge fused link.

 

well that would be a shorter run, ok, can I just solder in a 16 fused link? I dont need another close call, let alone a fire.

 

Yes, you can do that. Replace the wire from the alt to batt with one from the alt to the starter solenoid, will need a fuse link, bigger than a 16 though. Remember, all the car's juice runs thru that wire, battery charge and for all the accesories.
What do you have on the car other than stock?

 

Thanx Guys, I run twin fans (12") 20 amps or so total, MSD, that's about it except for "stock" full power accesories & added power seats.
Sixfooter,
when I run the 8 awg wire with the soldered in fused link (16 ga) can I run my fans power leads to the alt terminal for power?

 

The lead from the alternator calls for a 16 gauge link. The other lead to the lights is a 12.

Why not run your fans lead to the fuse box "ign" terminal with an inline fuse holder? That way you won't accidently leave them running if they're wired to a manual switch. Or to the "batt"terminal if you're using a thermostat control.

 

I can run the fans to the batt terminal, it's just so convienint as the alt is right by the temp controller. Would it hurt anything using the alt terminal?
Also the fused link, you mention a 16 ga, what exactly is a fused link (excuse my elec ignorance) does it just solder in line?

 

A fused link is just a wire designed to burn up if there's a short to prevent major harness damage. A good auto parts place can help you out with a length of it, just solder it in near the end.
Those white things in my pic above are the factory connectors with the last 6" or so the links. If you have a factory underhood light you'll see a connector like that near the light connector.
I suppose you could hook the fans up to the battery terminal at the alternator, just doesn't look "finished" to me, but that's my opinion.
I would still put an inline fuse holder on the fan line, tho.

bomb, this may interest ya http://forums.corvetteforum.com/show....php?t=1694955

 

Thanks for the info,
I just gone done running a 6 ga lead from the starter to the alt w/ a 16 ga fused link (napa). NOW, there is also a neg coming off the alt that goes back to the battery, is that BUBBA or kosher?

 

Thats a Bubba. What is needed for the Battery Neg is just the large black cable that goes to the frame. Now having said that, you need several Ground wires all over the place connected to the frame, including the alternator

 

Sorry, too confusing to read all the above.....take a 8-10 ga wire from alt stud to battery or more properly to the horn relay/power dist point mounted on driver's fender liner...large stud....and from there to through a ~16 ga wire to the battery post on the starter...so there are only two wire loops under tha heavy bolt....our 16 ga current limit wire about6" or so long into the 8-10 ga wire to the alt, and the heavy battery + cable....negative batt cable goes to frame under batt box....
there is a heavy battery to engine ground cable under pass engine mount to engine mount bolt on engine itself....which is obviously the alternator ground, no other wire needed.....

now I have dual Spal fans, so I take the power from frame up front, and directly off the alternator stud...with current limit 16 ga wire about 2" long....call it a fuse if you want.....I take ALL other power off the horn relay stud which is main power dist block feeding everything....
from alt out stud to that block is a 8 ga red wire......so there are two wires on that alt stud...one for the fans, the other for rest of the car....

that is it....no other wires than the two 1/2 inch heavy battery cables go to the battery.....period....

that is how a car is wired, there should be no other 'variations'.....it's the most simple, least complicated idiot proof way to wire any car....

 

I would run my correct fan relay high amperage wires directly off of the starter. No fan just draws 20 amps.

 

Confusing, kinda, thanks for the help but the 78 doesnt have the horn relay / power disrtibution block you speak of, if so mine is missing. I just ran a 6 ga wire from the battery post on the starter w/ a fused link, this I ran to the positive stud on the altenator. The fan is the only other lead going to this positive stud on the altenator. I have no clue why someone ran a neg off the ground on the alt to the battery???? This I'll remove. The only other ground coming off the alt is a thinner 16 ga wire that goes somewhere into the harness. I am getting a lil miffed trying to figure out what someone was trying to acomplish running the pos & neg off the alt directly to the battery? I do have the other ground straps mentioned at various spots on the frame, block, starter, power ant, etc.

 

You DO have TWO fused leads going to the starter terminal? One is for the lights, one is basically everything else(the one from the alt). Do you have lights now? If so, sounds like ya got it right. And there should be a ground wire connected to a bellhousing bolt directly behind the starter. Probably the ground Bubba brought all the way back into the battery box.

 

Yes, I have lights and that seems correct, also there is a thinner black wire that does go to the bell housing, so that seems good. Thanks for all the help Guys, I'll see shortly if all is ok. Now that I have the wires hooked up correctly I'll run it tomorrow and test.