Wiring Question

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74DartSwinger360

74DartSwinger360

The Brat Pack
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Valrico, Florida
I am planning on doing the MAD ampmeter swap and was wondering what else I would need to do to run a larger alternater say 100-120 amp range?
What wires should I step up the diameter on?
Plan on running a pair of relays for the headlights and one for the wiper motor and windshield washer bottle motor.
Any help and other mods to not have problems inn the future would be appreciated.
Thanks
 
EDIT: Misinformation in my first reply, I removed the misleading info & replaced with correct info.

I'm not sure what gauge wire would have come on your Dart originally for the alternator, but if you are doing the MAD mod, I would run a 6 gauge wire from the alternator directly to the battery, then run the same to your starter solenoid where everything else ties in. I created a central power buss for mine, but running it to the starter solenoid will work just fine.

I may be new to building an A-Body, but not new to wiring or building up hot rods lol. If you have any questions, post it up or shoot me a PM.

Rob
 
I'd run more like no6 with a 100A or larger. If you cannot figure out how, look for a local electrical contractor or two way shop that works with radio site work. We used to use lots of that in grounding, etc.
 
I concur with 273, he knows his stuff. I didn't think about looking up an electrical contractor that does radio site work, great idea.
 
Yes and according to the Delco site, they might recommend larger wire on even smaller alternators. I assume this might be because so many today are "one wire" and that means that resistance in the charging lead when under heavy load/ charge will cause the load voltage to sag across the charging wire -- that is-- with a "one wire" the regulator is sensing right at the alternator. The regulator doesn't know if there's a 1A load or a 100A load, it still maintains 14V AT the alternator.
 
Thanks guys. What do you guys recommend for a 85 or more amp alternator that plugs into the factory system? Could I run the wire from batt to alt Down the inner fender off the alt then under the radiator support and up the other inner fender to the battery? Is that direct enough?
What are some good high amp relays out there?
I know basic wiring but am new to most of this and will definately be askin tons of questions along the way.
 
I don't like running wiring low in front like that. I'd either duplicate original, run back on the engine, over on the firewall, and past the bulkhead to the stud on the starter relay

I cheated on mine. I just happened to have a length of wire made up with ends, "for now." It runs from the alternator, across the front on top of the water pump, and right over to the relay next to the ground cable.
 
The main current flow is to recharge the battery after starting. For a SB, just run the wire from alt stud to Batt+ right across the timing cover. That is how it is done on the Magnum motors. Indeed, just take the cable off a Magnum motor as I did. I think they have 85 A alternators. My cable goes to a relay box first (added), but you can get a battery terminal to bolt the lug to.
 
74DartSwinger360 said:
So your system the alternator powers the relays directly and then to the battery?
Click to expand...
The relays+ and Batt+ are off the same rail, other than a 100 A fuse on the alt output and 180 A fuse on BATT+ lead, and fuses on all relay supplies.

Instead of the MAD ammeter bypass, my ammeter is still active, but excess current is shunted around it thru forward bias diodes (in parallel) as the current output increases. You can read my post, but too complicated for most, so I suggest just bypass the ammeter.
 
74DartSwinger360 said:
Would it be better to run it straight to battery or to starter relay?
Click to expand...

I like to run it to the starter relay. I like to keep connections right at the battery to a minimum, as they are subject to corrosion. You can either run the main battery cable to the starter relay stud, and a second cable down to the starter, (mine) or run one long cable from the battery to the starter, and a second one from the starter back up to the relay stud. That stud has always been a handy hookup point for heavy loads.

The disadvantage of having two cables on the starter is that they are that much easier to rattle loose.
 
I don't think "engine out" helps much since all the wiring is above the engine. For a daily driver you might look at the Battery Brain. I put in all my cars and already saved me from being stranded a few times. Some models have a remote that helps as anti-theft. It also adds rugged wiring terminals close to the battery.
 
It wont be a daily driver but will get out during the week to school and stuff and all the time on the weekends. I already have MSD and am purchasing an MSD distributor. Will be replacing the underhood harness with one from evanswiring.com. And the doing the MAD Ampmeter conversion. Relays on each of the headlights and one on the wiper motor and wiper fluid pump and my electric pusher fan and front driving lights.
I also plan to put power windows and maybe locks, A/C, And a decent stereo. LEDs in place of the incandesents
 
Here's a chart I saved that has amps + length of run and wire gauge suggestions

WiresizingchartBW.jpg
 
Is that chart supposed to be only for the alternator charging wire?

100A is a bunch on a piece of no10, and .44v is a LOT of drop if you are talking about load voltage.
 
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