worship79

Alright, I've read just about every topic I could find on the forum and outside it. From Carcraft to Steve's nova site to MAD and other harness suppliers websites.

However, on a few crucial issues people just don't seen to agree.

So, here goes: 1979 Corvette, GEN light and voltmeter. Already has beefy stereo, Accel Super HEI 40k and H7 Euro headlights 55watts+ each and low beams are interconnected (so I have four low beams).

Planned mods: elec. fans, fuel pump and possibly waterpump too.

CS-130 alt I already had died on me the other day and I've been offered a new Delco CS-144, 140 amp for a bargain price.

What I can't find consensus on is the following:

- to run a heavy gauge charge wire to either the starter, horn relay or battery... Or not all?

- If so, 8 gauge, 6... 4?

- to fuse it, inline fuse it... Or not?

- to maintain the original charge wire next to the new thicker one

- to run accessories directly from the alt or from the starter / horn relay / new junction

- to ohm the sens wire even if you have a gen light or not

I hope someone can help out, because I'm lost in the woods here.

Thanks!

- what the best route for the theoretical new charge wire should be: along the front across the radiator or asking the firewall.

'75

I would run an 8 ga wire parallel with the existing charge wire along the existing harness along the firewall to the starter and use a 12 ga fusible link near the starter. Your 79 doesn't have the heavy duty horn relay like early c3's. For future expansion such as fans you can either hook directly to the alternator or the starter for power.
Some have not beefed up the charge wire using the reasoning that their electric fans are hooked to the alternator, what they don't factor in is that if the battery is severely discharged, the alternator will try to force all 140 amps through whatever wire is there and the factory wire is inadequate.

7T1vette

Probably why your 130 amp alt died. It's been calling for max charge most of its life, because the wiring you have isn't capable of feeding that many amps to the battery. Basically, "You can't feed 10 gallons a minute through a straw...".

Do as suggested above. Add additional wire in parallel with your existing wires. Pull off the fans ASAP; then you can reduce the size of the additional wiring, thereafter.

P.S. I can tell you are only thinking about what to do with the [+] positive 12vdc wiring. If you have any grounds involved with that high amperage (other than the battery wiring, which should be plenty large enough), those need to be larger, as well. {The fans should be grounded directly to the frame; not through any other hardware, like the radiator support.}

Richard454

Here's my .02cents....I was in the 12V industry for about 20 years....some of course, will disagree...others will say "it worked for me..."

Wire (insulated) is rated when the insulation melts..and the rating is at 70°F...obviously hotter under the hood...and another variable- as the temp goes up- so does the resistance...that means it'll take more power to do the same work...

8gu should work fine- 6gu won't hurt...the starter has a large gauge wire coming right from the battery so that's OK to connect there. I feel running it to the battery is the best- that's what high-end European cars do...

Fuses? Wired correctly- away from harms way- I think you'll be OK without- the battery to the starter is not fused...


The battery is the best place to go for power...NOT the alternator...The battery takes the surges fine-like every time you start the car... the alternator not so well...Figure when the fans start up-they PULL a tremendous amount of current- almost looks like a short circuit to the alternator...PLUS the car is usually idling and at the low RPM the alt is not capable of putting out max current - depending on pulley that's usually around 1200-1500 RPMs...


Think of the battery as your bank account...the alternator as your income... and the smaller the wire, the larger the banking fees...

You would not want the mortgage payment coming directly out of you paycheck....

Richard

worship79

Alright, this I can do, thanks guys! I'll look into it and reroute some cables.

Good thing I checked the lights by the way, my bulbs need replacement.

ezobens

I'm currently upgrading the cabling in my 69' and you can never go wrong by erring on the side of larger cables. I'm replacing my factory 2 gauge battery cables for 1/0 gauge (also replaced the problematic side post with top post terminals) and running a 4 gauge cable from my starter to the CS-144 alternator. I'm also running a 6 gauge lead from the alternator to the horn relay. I am not removing any of the existing factory wiring (other than the battery cables).
The individual components get fused, not the main power buss. Also, the shorter the run the better- I ran my power along the firewall vs up and around the core support to keep the cables as short as possible.
I'm no EE but this approach has worked well for me over the years.