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Wol Gemut
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Discussion Starter · #1 ·
So, I want to upgrade the "Big Three". Appears the battery to chassis ground has already been done by the shop though that could be upgraded also but that is the easy one.

In the attached photo, the wire shown in yellow is the chassis to engine, correct? It actually connects it appears to the loom running the alternator to battery power (red), correct? So where does the chassis to engine (yellow) wire end up? Will I be able to see it from underneath? Does it run to the alternator negative post? (One guy on youtube said that is a good way to do it.) Insights greatly appreciated!

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Wol Gemut
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Discussion Starter · #3 ·
Should be the ground to the battery. The start grounds to the block. I'd have to look at mine again.
Only grounds on the block are for the engine harness.
I do not understand Mick. If the only ground on the block is the harness, why is it said that one of the "Big Three" is negative chassis to engine block.
 

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Wol Gemut
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Discussion Starter · #4 ·
I see now that loom into which the two wires go actually ends at least for one of the wires just a little bit further at the lower location circled in yellow (I previously thought the loom ran to rear of engine). I am thinking that either of the bolts circled in yellow would be a location to run an additional chassis to engine ground?
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I do not understand Mick. If the only ground on the block is the harness, why is it said that one of the "Big Three" is negative chassis to engine block.
The big 3 have nothing to do with the stock layout. So just upgrade how it normally goes. You can add the ground anywhere you want. Plenty of holes all over the head and block.
 

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Seriously?
2004 Pontiac GTO, LS1, 6 speed, Quicksilver/Black
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Any good metal contact will work for a ground. Regardless of how the stock setup is, ground the engine and the chassis, then run a cable from the alternator positive post to the battery positive and you should be golden. I have yet to do this on my car as I have been waiting to do it when I revisit the stereo system, someday...
 
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2004 Pontiac GTO, LS1, 6 speed, Quicksilver/Black
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Yes... What is our alternator output? 140 amps? Whatever it is, add a fuse or fuse link in that amperage to protect that cable and the battery and alternator should a short ever happen. Same principle as fusing your amplifier power wire...
 

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Wol Gemut
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Discussion Starter · #9 ·
Note with that positive cable you might be bypassing the fusible link or main fuse, don't want to do that-
Yes... What is our alternator output? 140 amps? Whatever it is, add a fuse or fuse link in that amperage to protect that cable and the battery and alternator should a short ever happen. Same principle as fusing your amplifier power wire...
I am unclear on this. The alternator positive runs directly to the battery positive in our cars, correct? So why when adding another positive alternator cable to the battery positive would I need to fuse it? I believe Konnie the Goat states this in this long ago thread:

 

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2004 Pontiac GTO, LS1, 6 speed, Quicksilver/Black
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I am unclear on this. The alternator positive runs directly to the battery positive in our cars, correct? So why when adding another positive alternator cable to the battery positive would I need to fuse it? I believe Konnie the Goat states this in this long ago thread:

As Fox stated, the factory wire from the Alt to the Battery has a fuse link on it that will melt if overloaded. You don't want to add an upgraded wire in parallel to that and not protect it. In that thread you linked, Konnie is talking about ground wires. You don't fuse ground wires, only positive battery current carrying wires. That is why I included the reference to wiring up an amp... you wouldn't run a power wire to it from the battery without fusing it. Your Big 3 alternator to battery wire should be protected as well.
 

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Wol Gemut
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Discussion Starter · #11 ·
Got it, thank you. Re-reading the thread, it was not Konnie but tusk in #16 who claims the factory alt positive was a direct shot with no fuse.
 

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2004 Pontiac GTO, LS1, 6 speed, Quicksilver/Black
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You can run it without being fused. I have done it before on another vehicle with no problem. I have also had a factory fuse linked wire melt and start a fire on an old POS Camaro I once owned. I would fuse it on the GTO.
 
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2004 Pontiac GTO, LS1, 6 speed, Quicksilver/Black
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Where is the factory fuse? Pulled the entire harness out and there isnt one there. Deleted all of it and just ran a 1/0 wire with a fuse.
I have no idea as I have never messed with it. I'd be surprised if there wasn't a fuse link on that wire.
 

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When I upgraded my ground, I had BatteryCablesUSA make me a 'Y' cable from 2ga. One end has a 5/16" right angle terminal for the battery post, the middle has a straight 1/4" terminal for connecting to the body stud, and the other end has a straight 3/8" terminal for connecting to the block. This made it easy and clean to upgrade both grounds at once.

You can see how I routed it in this pic (the blue line). I terminated it on a starter AC compressor bolt.

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Battery Cables USA makes great stuff, and ships quick at a flat rate.

To get a Y cable, you basically order two cables, and leave one end as "No connector". Then add a note telling them how to join the two to create a Y.

Here is what I ordered:

2 Gauge (2 AWG) Marine Grade Tinned Copper Battery Cable UL1426 Flexible with ends
Choose Color: Black
Length (hole to hole): 30 in
Choose Connector End #1: 1/4 inch (M6)
Choose Connector End #2: 5/16 inch (M8)

Product ID: BC2BK-30IN-14-56

2 Gauge (2 AWG) Marine Grade Tinned Copper Battery Cable UL1426 Flexible with ends
Choose Color: Black
Length (hole to hole): 13 in
Choose Connector End #1: 3/8 inch (M10)
Choose Connector End #2: No Connector This Side

Product ID: BC2BK-13IN-38-NONE

and here was the note I added to the order:

Please make the 5/16" ring terminal on the 30" cable a 90 degree bent lug. These two cables are meant to be a 'Y' cable. The bare end of the 13" cable should be inserted into the 1/4" end of the 30" cable.

This ended up costing me $20.72 shipped
 

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Oh, and on this part:

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I'd recommend you take everything off the stud, then use some sand paper to sand away the paint and get down to bare metal around the stud. Then put the largest connector on 1st, and stack the smaller ones on top.

You're not going to get a great ground connection the way it is situated now.
 

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Wol Gemut
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Discussion Starter · #17 ·
stoopalini, this is great information. Incredibly just this weekend I placed my order with Battery Cables USA, I wish I had had this info first. I still might switch to it even though it is too late to cancel and change (they already sent tracking number). and now I know for sure a good engine block ground. What are your thoughts on grounding to the engine at the red circle? This is what I measured to, and also the bolt size I measured for.

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Hmm, the red circle doesn't appear to be on any bolt on my screen? It's on the AC line

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Above the red circle is the motor mount, is that what you mean? I used one of the AC bolts myself (I mistakenly wrote "starter" above ... but it's the AC compressor bolt I used).
 

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Is it one of these you meant to circle?

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I wouldn't use 4, as that one holds the pressure in the AC lines.
I wouldn't use #1 either, although it would work. That is part of the motor mount.
I used #3 on my car
#2 would work just as well, it's more difficult to get to though.
 
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