Well, I've posted these questions up in my build thread, but only got one answer, so I'm guessing that the people who have the answers haven't been reading it... Oh well, if I post up the question here (with an appropriate title), then maybe I'll have a better chance of getting the answers I need (as well as helping others who might be looking for the same info!)...



OK, I'm working on the electrical lately, & even though I've done some searching, & looked at a bunch of threads on here, I guess it's time for a few questions...

Don't remember if I've mentioned it here yet, but I'm relocating the battery into the rear hatch area. I have an NHRA-approved sealed plastic box that it's going into, and 0/1-gauge marine welding cable (LOTS of rather-fine-gauge, individually-solder-coated copper threads) going from the battery to the starter, but after reading all of these other threads, I'm thinking that I'll want an equivalent negative battery cable going from the battery in the rear hatch area to the engine block. (I'd initially thought that I'd just run a heavy-gauge cable from the - battery terminal to the rear part of the (solid steel bar) SFC, & then another from the front part of the SFC to the block, but after reading some more, it seems like that might not be the smart way to do it...) I already have two fairly heavy-duty (1" wide?? maybe a bit more??) ground straps going from each cylinder head to the frame rails, but I don't yet have any ground straps connected to either the engine block or the subframe connectors... Are those a necessity, or just a "nice to have"??

The alternator charge wire - I have a 4-gauge (?) (probably overkill) cable that is long enough to run from the alternator to the battery. It's always seemed to me like there should be some kind of device in-line, something to regulate the current. Is the charge cable just something that runs (essentially) parallel to the battery cable, with the charge being regulated by the difference in potential?? (In other words, am I trying to over-think this??)

Fuse box - What gauge wire/cable should I run to that? I'm thinking that the 4-gauge cable should be just about right... I also have 3 or 4 "buss bars" that I've grabbed from GM trucks in the junkyard for convenient "hot" or ground attachment points, any suggestions for those??

Thanks in advance guys, I'm sure they're some fairly basic questions, I just wasn't able to find the answers when I was looking yesterday...

EDIT: I don't want to be a PITA, but I've set myself a goal of getting this car RUNNING in time to make the BIGGEST, BADDEST car show I've ever seen in my LIFE (last year, 6,000 cars showed up!!) And it's only a MONTH away...

 

I've got a short (18"?) neg cable from my trunk mounted battery to the chassis (unibody, too) and have the engine and battery grounded up front, all runs with #2 cable. My alternator is #8 and runs through a 120A breaker, running straight to the starter post (for convenience). Mine's pretty simple though, carbed with an MSD box and not much besides the fan that draws big current...

 

I'm a big advocate of running black ground wires to every possible load. People like to say 90% of all electrical problems are related to grounds. Well doesn't it just make sense that if you get rid of grounds then you will eliminate 90% of all electrical problems? If you look at new cars, especially the computer circuits, they all run dedicated black return wires to each load. Cars aren't built as throw away items anymore.

If I were you I would run an equal sized battery cable up to the block.

Like you I have a 4 gauge wire from the alternator. I don't run it straight to the battery though, I run it to a small power distribution box up near the motor. I then branch off of that with an 8 or 10 gauge wires to my battery, fuse box and a third to an electric fan. The power block is sort of neat, I got it from a car stereo place. It has gold plated lugs for the heavy gauge connections and separate smaller lugs with fuses for the various loads. You can even buy ones with build in digital volt meters.

In your case you could do like S10xGN and run the 4 gauge wire to the starter lug. Like him use some sort of in line fuse right at the output of the alternator.

This guy has a pretty good write up of how to set up a proper electrical system

 

On my project I did exactly what you are doing, I used 4 Gauge High quality welding cable for my power feed from the battery to my starter, and the same 4 Gauge lead from the alternator to the starter (convience and cleanliness see my build thread). I run a ground strap for my engine to chassis, and from my battery to chassis. Only thing i did that was out of the ordinary was I linked all of my engine grounds (sensors) to a 10 gauge wire i believe, that grounded to each head and the block, then also ran back to the PCM, then a 8 gauge wire ran all the way back to the ground on the battery. My thinking is the car can start just fine with the chasis ground ( I have less than .5v drop while cranking with 8 gauge ground wire disconected to verify i wasnt overloading it, and it is fused) but i know that even a slight voltage drop can really screw up senosor/PCM readings. Hope this helps.

Most cars run ground wires to common grounding points on the chassis in new cars, not all the way back to the battery.

Mark

 

Hey guys, thank you - seriously!! I'm sure that this probably seems pretty basic to a lot of people, but with that show coming up so quickly, I really don't want to have to waste time going back & re-doing anything! And while it turns out I had a pretty good idea of the overall picture, your answers have helped me with some of the details.

OK, I'm off to get a couple things done, & then into the garage!!