Battery wiring

[Ghost's68]

I’m sitting here thinking about finishing up my wiring and have gotten to the battery. As far as I know, the battery will have to run a large gauge wire to the starter and a smaller gauge wire from the alternator to the battery for charging purpose. Negative cable will go to chassis ground and another negative cable from engine to chassis also.

Does this sound correct? Also what size gauge wires should be used? Anything else needing to be fed from the battery?

Thanks in advance

[mongocanfly]

on mine I always run ground cable from battery to the engine...then ground from engine to body and to frame...
the size wire depends on how far you are running it from battery to starter....

[Flubyu]

OK, so I just ran a ground from the battery to the engine block. Engine starts and runs. Should I run the additional grounds? I know this is a rather novice question...

[BR3W CITY]

My battery is rear mounted so I use a larger gauge cable to be safe, but all my battery stuff is 0awg. The wire to my starter and some other high amp supplies are 4awg

There should be a ground from chassis to battery. From engine to chassis. From heads to block (at least one, the upper wiring for injectors etc has had errors from lack of grounding the heads). There is at least 1 woven ground strap on there from the factory, if not more. More ground has never hurt anything.

[mongocanfly]

I'd never heard of grounding heads to the block...new one in me....
but more grounds never hurt. ..

[DLW]

That sounds right.
My battery is mounted at rear frame rail as well, so I use 1/0 cable, plus I have a 175 amp alt.
Like mentioned, battery cable size is determined by length and amperage needed.
For ground, I went to frame rail because it its mounted in back, then I ground block to frame and frame to cab, and also from heads to cab and frame. If the battery was in front I would go to engine block first, then frame rail to block. LS engines should have the heads grounded, coils, injectors etc need good grounding.

[BR3W CITY]

Originally Posted by mongocanfly

I'd never heard of grounding heads to the block...new one in me....
but more grounds never hurt. ..

Look at the back of your heads, there's a mesh strap from the head to the block on most of em. Can't say everyone, but I've seen it more than a handful of times. I usually save extras off various junkyard motors and toss them on when I do stereo's or am making up for an undersized big-3. I usually see it from around the fuel rail protector on the back side of the 02/3/4/5 trucks.

Like these


I was told it helped with intermittent electrical issues on the electronics that ground locally at the head (mostly the coil and injector harnesses). This could be complete horsesh!t, but it made enough sense for me.

[mongocanfly]

good to know if there's issues that could be the problem. ...I looked at my 02 lq9 and I don't see any head to block grounds...my ls3 doesn't have the grounds either but does have a ground coming out of the injector harness on d-side....

[Ghost's68]

Awesome! Thanks guys for all the help. A buddy of mine is letting me barrow their crimper, hopefully I’ll be able to knock out the wiring this weekend. I too also have the mesh strap but PO went from heads to frame rails. I’ll reuse that for grounding heads to block. My new harness did come also with a built in ground. I tied that into the back of the passenger side head.

[DLW]

Originally Posted by mongocanfly

good to know if there's issues that could be the problem. ...I looked at my 02 lq9 and I don't see any head to block grounds...my ls3 doesn't have the grounds either but does have a ground coming out of the injector harness on d-side....

I am not sure you have to have a ground on the heads to block/frame/firewall for the engine to operate. But a lot gremlins have been traced back to there. If your working OK, then should be fine.

Just for reference, the 2014 Camaro I got my LS3 from had a 1/0 size cable from the head to the firewall. My 00' Camaro hadna braided one from head to firewall. My 2017 Sierra has a braided one from head to firewall. So, I ran one as well from the head to the firewall on the 66'. If nothing else it will act as a noise suppressor and a ground to the cab body.

[mongocanfly]

yeah I've got the ground from head to firewall as well...just not from head to block.....that's odd...you'd think all them head bolts would be enough ground....haha....
my lq9 harness also has a harness ground to the head like the ls3...