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Proper ground for 73 engine, charging system? Not sure if I have this right.
#1
Hello,

On my 73 vert with gauges and a tach, the only ground on my engine and charging system is from the negative battery post to the engine block. One large cable. I've seen other pics on the forums that show grounds on the voltage regulator and other places I think. This is not a 70 amp alternator. Here's a picture of the alternator harness, note that there isn't a ground wire. Am I missing one? Is the 73 unique that way? I'm fighting a short somewhere and want to make sure I've got the basics covered first.

Help!

[Image: 2e0qx3n.jpg]

Scott
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#2
Im sure some one will come along with the anser..But i think 73's do have a diffrent wiring harness.
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#3
Based on the presence of the white wire with black stripe and the square connector, I'd say the harness is likely correct. The correct negative battery cable has ground tab in the middle of the cable length. This tab is to be bolt to the bottom regulator base hole with a sheet metal screw and toothed lock washer. Chuck
http://www.martiauto.com/itemselection.c...editem=yes
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#4
c9zx;99577 Wrote:Based on the presence of the white wire with black stripe and the square connector, I'd say the harness is likely correct. The correct negative battery cable has ground tab in the middle of the cable length. This tab is to be bolt to the bottom regulator base hole with a sheet metal screw and toothed lock washer. Chuck
http://www.martiauto.com/itemselection.c...editem=yes

You are absolutley correct Chuck. If I'm not mistaken that serves as the ground for the regulator as well. A lot of components such as the horn use where thet are bolted to the body as their ground. Remember. For testing shorts, leave the negative wire off the battery and measure from the battery negative to ground on the body. If you have voltage you have a short!

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#5
marks73;99578 Wrote:
c9zx;99577 Wrote:Based on the presence of the white wire with black stripe and the square connector, I'd say the harness is likely correct. The correct negative battery cable has ground tab in the middle of the cable length. This tab is to be bolt to the bottom regulator base hole with a sheet metal screw and toothed lock washer. Chuck
http://www.martiauto.com/itemselection.c...editem=yes

You are absolutley correct Chuck. If I'm not mistaken that serves as the ground for the regulator as well. A lot of components such as the horn use where thet are bolted to the body as their ground. Remember. For testing shorts, leave the negative wire off the battery and measure from the battery negative to ground on the body. If you have voltage you have a short!

Well it looks like a PO changed out the correct battery cable with just a straight length of standard battery cable, thus no ground to the body. Until I can get the correct cable can I get away with running a ground wire from the block to the voltage regulator base screw?

Scott
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#6
Monterey;99584 Wrote:
marks73;99578 Wrote:
c9zx;99577 Wrote:Based on the presence of the white wire with black stripe and the square connector, I'd say the harness is likely correct. The correct negative battery cable has ground tab in the middle of the cable length. This tab is to be bolt to the bottom regulator base hole with a sheet metal screw and toothed lock washer. Chuck
http://www.martiauto.com/itemselection.c...editem=yes

You are absolutley correct Chuck. If I'm not mistaken that serves as the ground for the regulator as well. A lot of components such as the horn use where thet are bolted to the body as their ground. Remember. For testing shorts, leave the negative wire off the battery and measure from the battery negative to ground on the body. If you have voltage you have a short!

Well it looks like a PO changed out the correct battery cable with just a straight length of standard battery cable, thus no ground to the body. Until I can get the correct cable can I get away with running a ground wire from the block to the voltage regulator base screw?

Scott

That or from the ground terminal of the battery to body. That's what the PO on the 72 did.

[Image: 2rr7aiv.png]

Just cruising along minding our own business when BAM!!! The LAWS show up.
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#7
ground is ground is ground.

Get a good battery to block ground. Then a good engine block to body ground. Then make sure anything that has a ground is, well, grounded to either the block or the body.

You run the battery to block first (instead of to the body) because of the starter, nothing sucks up more amps.

You can also run battery to block, battery to body. That's what I do.

'Mike'
73 Convertible - 351C/4V CC heads/4bolt/forged flat tops/comp 270/rhodes/mallory unilite/tri-power/hookers/glasspacks/c6/3.50 limited slip/Gear Vendors/Global West sub frames, strut rods and shelby style traction bars/ Rear sway bar/tilt steering (not original)

Pics of modifications included in:
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#8
Ditto. Run an additional ground wire to the regulator from the battery neg. Make sure you have bare metal contact at each grounding point
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#9
Bill73Ragtop;99705 Wrote:Ditto. Run an additional ground wire to the regulator from the battery neg. Make sure you have bare metal contact at each grounding point

Thanks all for making this a simple fix. Created a grounding wire to go from the battery to the body via a connection to one of the voltage regulator mounting screws.

I don't have a ground from the block to the body other than by the negative battery cable connecting to the block. Should this be adequate or should I also create a ground wire from the block to the body?

Scott
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#10
Monterey;99733 Wrote:
Bill73Ragtop;99705 Wrote:Ditto. Run an additional ground wire to the regulator from the battery neg. Make sure you have bare metal contact at each grounding point

Thanks all for making this a simple fix. Created a grounding wire to go from the battery to the body via a connection to one of the voltage regulator mounting screws.

I don't have a ground from the block to the body other than by the negative battery cable connecting to the block. Should this be adequate or should I also create a ground wire from the block to the body?

Scott

Scott, If I understand what you have done with an additional ground from the negative battery cable to ground at the regulator, you should be good. Chuck
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