Wiring Panic

[bobs66440]

Ok, I am doing my meditation exercises trying not to go into complete mental meltdown while wiring the car. I bought a Rebel 9 circuit kit hoping that it would include instructions for completely clueless morons like me, but it doesn't. I am running a GM HEI ignition system and incredibly, it has a schematic for a GM points ignition, but not HEI . Go figure. But I was able to search the forum (between sessions of blowing into my paper bag) and found what I think is the correct routing. I also learned that 2/0 welding cable is good for the battery cables. Check.

Anyway, I know that grounds are really important, especially on fiberglass cars, so I learned to ground the engine to the frame (I bought a braided ground strap for this) and ground the (-) side of the battery to the frame also.

My questions are:

-What size ground wire from battery to frame?

-Whats the best way to ground everything on the car without having a million individual ground connections to the frame?

-I'm attaching the fuse block to plywood on the firewall. Should I run a common ground connection under the dash or pick one or two spots on the chassis?

-Apparently I have to make up all new ground wires for all the stuff under the dash. What gauge wire should all the ground wires be?

-Is there anything I'm missing or any tips or tricks? Remember, I've never attempted anything like this because my mind draws a blank and goes into stupid mode whenever I think about wiring. I would buy one of those how-to books but I don't think my nerves could take reading it...

Thanks!

 

[T-Test]

I use a ground buss bar from an electrical panel. Can be bought from Home Depot or Lowes or any electrical supplier. Run a 10 gauge wire from the battery to the buss bar and then to the frame and then terminate all grounds from components to the terminals on the bar. You can get different lengths of buss bars, depending on the number of terminals you want, and you can put more than one ground wire under each terminal. Hope this helps?

 

[madmike8]

https://tbucketeers.com/threads/wiring-diagrams-for-a-gm-system.5996/

Try here...

 

[Lee_in_KC]

My experience has been that improper/inadequate grounding is the most common cause of electrical problems in hot rods. I am a big fan of dedicated ground wires for every load, all routed to a common ground buss with a dedicated cable to the battery. I happened to use the Ron Francis ground kit, as it includes labelled wires for everything electrical you could imagine on a hot rod. A bit spendy, but worth it in my opinion. I also ran a ground cable directly from the battery to a starter mounting bolt rather than a cable from the block to the frame. I did not use the frame as ground for any load.

 

[PotvinGuy]

What Lee says. Forget the frame as a grounding point. But you must ground the engine to the battery for the starter and some senders. Like Lee I do this by running a heavy ground cable from the battery to a starter bolt. Other than that I use 16 gauge for ground wires. Let us know if you would like diagrams. I've wired all my cars from scratch, never used a kit, and I've made all the mistakes and found the pitfalls. My latest electrical panel may be a bit of overkill:

...but it was fun to build. Oh, I use the fuses that light up when they blow. Really helps troubleshooting.

 

[bamabucket]

I used some of the wiring methods mentioned above. Like T Test, I use an electrical panel bus bar for a central grounding point. The bus bar is grounded with 8 gauge wire to the frame and also to the starter bolt where my battery ground cable is attached. The engine is also grounded to the frame. I have run a separate ground wire from each load to that bus bar, as Lee recommends. It is a little more trouble to run a separate ground wire from each load, but wire is cheap and you don't need that much for these little cars - it is well worth the effort and will eliminate some electrical problems that can be hard to diagnose. You didn't mention relays, but should use them - I did as Potvin Guy and didn't use a kit and have relays for the individual loads. My car is not even close to his in terms of build quality but I haven't had any electrical problems since I rewired my car this way.

 

[Keeper]

I used the same harness. I used 3 grounding straps.

One 3/8 wide one on each side of the engine to the frame.
One 3/4 wide one from the engine to my steering column mount on the inside, I also used that mount as the main ground point for the inside. I ran a 10g ground wire from a grounding bus to the mount point where the 3/4 strap came in.

I then grounded all my interior stuff to the grounding bus.

I thought I had pics of that but I do not.

Oh and the pink wire goes to the HEI batt terminal.

 

[bobs66440]

You didn't mention relays, but should use them - I did as Potvin Guy and didn't use a kit and have relays for the individual loads. My car is not even close to his in terms of build quality but I haven't had any electrical problems since I rewired my car this way.

When you say relays, I'm not sure what you mean. I know the horn has a relay I think...I have heard of headlight relays. I'm not sure what they are or what they do. I know, I shouldn't be wiring a car, lol...

 

[Keeper]

haha we all went through it!

Rebel sells a relay kit for the headlights, its just a safer way to wire the headlights and allows them to work without the dimming that sometimes happens with some setups. Not required at all, but recommended.

 

[bobs66440]

haha we all went through it!

Rebel sells a relay kit for the headlights, its just a safer way to wire the headlights and allows them to work without the dimming that sometimes happens with some setups. Not required at all, but recommended.

Okay, is the headlight circuit the only one that needs relays?

 

[Keeper]

Well the horn one is built into the fuse block, so nothing additional needed there.

The reason they usually put relays on the headlights is to help with the dimming, since the regular setup has all the power running through the switch to the headlights. Using the relay kit moves the power off the switch and to the relay so the lights get a full 12v all the time.

As least that is how I understand it.

 

[Keeper]

I did not realize the Rebel relay kit was $50, I do not remember paying that much. I am sure someone on here can poke in with a how to on the headlight relays.

 

[Lee_in_KC]

If you have an electric radiator fan and/or electric fuel pump, you need relays for them. Actually, any load that pulls 10 amps or more at steady state needs a relay, in my opinion.

It seems like we've had this conversation before... I need to search old posts...

 

[Lee_in_KC]

Here is the thread I was thinking of... hopefully this will be helpful...

https://tbucketeers.com/threads/alternator-question.13028/#post-137613

 

[PotvinGuy]

I use relays for most loads, so that the wiring in the dash carries no significant current. And you don't need those overpriced kits; I get most of my parts from http://www.delcity.net/

 

[EX JUNK]

When you say relays, I'm not sure what you mean. I know the horn has a relay I think...I have heard of headlight relays. I'm not sure what they are or what they do. I know, I shouldn't be wiring a car, lol...

A relay is nothing more than an "electrical switch" that is activated from a "manual switch". By that I mean, your head light switch does not have to carry the higher current through its contacts. Instead, it turns on a relay which requires very little current and smaller gauge wire. The contacts in the relay close and deliver the higher current to the head lights. The contact terminals on the relay have the heavier gauge wire to carry the higher current, thus saving the smaller contacts on the head light switch.

I hope that this rather simplistic description of the function of a relay helps.

Jim

 

[bobs66440]

Yes, that helps. Thanks guys. I really appreciate the input. Wiring for me has always been a weak point. For some reason, like algebra in high school, my brain just resists absorbing the information. But I'm learning now, so thanks!

 

[bamabucket]

Like Potvin Guy, I use relays for most loads. Using them involves a little more wiring (just like the individual ground wires) but is worth it to insure full voltage is delivered to the load and there is only a small load on switches. I don't want to come across like an electrical expert - I am definitely not. I was completely baffled when I started my rewiring but was able to learn what I needed from discussion boards, a few wiring books, and research on the 'net. After you get information on the basic principles you will find that it isn't that difficult. I wouldn't say that about a late model car because their electrical systems are very complicated as opposed to the relatively simple systems in our little cars

 

[Screaming Metal]

Been sitting here on the fence.....just do your wiring one circuit at a time. Electricity, flows like water does thru the pipes, but with electricity, its wires. Take your time and do it right.
99% of the problems with electrical on any hotrod is one of three things:
1. Too small a wire....
2. Loose or dirty ground wires
3. Loose, dirty, corroded or improper battery clamps.
4. Loose, corroded or dirty starter connection at the cable.
When doing something complicated, I'll run off 3 or 4 copys of the wiring schmatic. Whichever circuit I'm working on, I'll trace that cirduit out on the schmatic with a colored Hi-Lighter. I only work on that one color. After done with that one, put it in your tool box after testing it.
When moving from the headlights to say ignition, new copy with a new color, simple. It helps you keep track.
Chevys HEI only takes 1 hotwire from your switch. Nice thing also is theres a tach plug on the HEI, too.
Run a ground from your battery to your motor. I put it as close to the starter as I can. At least 0 ga., I would not go smaller the #1. I use welding cable, buts thats me. I use the crimp on copper lugs. also. Its strong, is flexable, and has really hi current carrying capacity.
Anything over 10 amps as you were told need a relay. I use a relay to turn on the headlights, and use another relay for the Hi-beams.
I use one on my cooling fan, one on my waterpump, one on my fuelpump.
I have a mains relay, ie, I have a covered toggleswitch that energizes a relay that energizes the fuseblock. That way if there is a electrical problem, I can kill the whole thing from the drivers seat. I also have a 100/200 amp breaker that should a starter short or solenoid sticks, it will kick out after cranking for too long. (The folks that have the big stereos use them to power those really hi-power amp systems.)
I know, I have it redundant on purpose. I had a starter stick and it melted all the insulation of that wire. that cable ran right beside the fuel line...so I've always done the redundant system.
Always run a ground from the battery to the motor. From the motor to the frame. I also go from the battery to the frame also. Connect your lugs with star washers....helps with making good contact.
At the rear of your car, run a seperate ground wire for your taillights. because the body is not metal, and your gonna need it for the lights.
I've seen great build cars become totally unreliable because someone didn't take the time to do the wiring right. I've never been stranded on the road from a electrical wiring problem.