Hi everyone, I'm a newbie, here's my first post..Just bought a 1969 z28,the battery is in the trunk.The negative cable is grounded to the trunk.I was told it should be directly to the block?? I do have some weird electrical stuff going on,nothing major(I don't think)

 

you can run a piece of AWG 10 from the trunk to the frame and from the frame to the block
I made a junction block for all my ground wires. 1 wire from the negative post on the battery to the junction block and then a wire from front and rear of the body, one for the frame and one for the engine block

 

Thanks!

 

Eight gauge would be better and better if actual run from the battery to the block - the current path is relying on body panels and the spot welds.
If you have a mechanical volt regulator, adjust it for the correct voltage at the battery posts, not elsewhere.
There is cable loss and connection loss of current.

If you have an internal reg'd alt, run the 12 GA sense wire to battery + post.

 

I would run a 4 gauge cable to the front and attach to the block. I would also Ground it in the trunk, from the block to the frame, from the frame to the body, from the block to the radiator core support. Having done low voltage systems most of my life and seen the horror stories of not properly grounded vehicles having electrical issues. From the factory there were several grounds and I would put them back on... I have covered most of them here...

 

I am not an electrician nor do I claim to be. if you go outside to your electric meter on your house, you will only see a #10 solid copper wire for a ground and most houses have a 220 amp service. way more than a car alternator will produce

 

I have my ground cable run through the trunk floor and attached to the rear "frame" section. Then a cable from the front subframe to the block. I also have welded frame connectors, so the subframe is a direct part of the unibody. Not having that, I would definitely run a cable from the battery to block. Taking the long run length into consideration, I used 1 gauge for the positive cable, and the ground cable, if going battery to block, wants to be the same gauge. With the positive cable, I ran it to a remote starter solenoid on the inner fender, and down to the starter. Then connected my one-wire alternator at the remote solenoid, because a remote alternator connection (situated closer to the loads like factory) works better than going directly to the battery.

 

I've done a lot of household electrical work. The ground wire you see is the one that's connected to a lightning ground rod that's pounded into earth, and connected to the panel box.
The common line coming into your house is a fat cable that's the same gauge as the other 2 hot leads. Open up your panel box and you'll see 3 cables coming in, the cable that's recoded with white tape wrap is your common. The common line is what completes household circuits, not ground.

 

AC and DC are totally different animals. However in the case of your home there are multiple wires from the electric grid either overhead or under ground. You have two primary and one neutral if it is a typical home service. The neutral wire is actually attached to a big ground rod coming from the power company. All the wires are the same size and the limiting factor is the size of the smallest wire. AC provides two bus bars on a typical home setup for primary and one neutral. When you insert circuit breakers (typical modern home) you attach to the bus bars, either one or both if you need 240 volts. The small copper ground wire pounded in to the ground below your meter is a secondary neutral to give a voltage problem somewhere to go should the feeds from the power company fail or be cut. It is a place for residual power from in the home to have a place to fail in the event of a power issue. Voltage will always try to find the shortest path to ground. Enough, sorry for the sideways in the thread..

 

Hey guys, thanks to all of you for the theory of both ac and dc current. It all started because I bought and installed a new Ron Davis aluminum radiator!I had to upgrade my stock alternator to 100 amp to allow for the dual 30 amp electric fans. So today I ran a 1/0 Awg from to trunk battery positive post to the starter,and then a 1/0 negative to the block there is also a grounding kit I bought from them to pretty much ground out the total system to prevent electrolysis. Wow I had no idea how important grounding is....