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Ground strap

pjm8047

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Is there any advantages to adding a groud strap between the block and the firewall? Would it help alternator output? I noticed that they stopped using firewall grounds after 69 any idea why?
 
Ground should be on you battery connection after a certain date. Two leads from the engine, battery and body ground. Make sure you have the right negative cable for your car.
 
Will adding grounds improve charging system?
 
Only if the ground you have now is no good.

Use a multimeter to measure resistance from alternator body to battery negative and a body point. Then run a temporary jumper from the alternator to those locations. If you see a sizable difference in resistance then you would address fixing grounds you already have.

Adding will not improve if you have a properly working system and grounds are clean.
 
I noticed that they stopped using firewall grounds after 69 any idea why?

well, my 74 got it.

Use it. Any ground reinforce is a help. Remember the bigger wire runs between batt and engine. The radiator core support barelly gets a 12 gauge wire or so.
 
well, my 74 got it.

Use it. Any ground reinforce is a help. Remember the bigger wire runs between batt and engine. The radiator core support barelly gets a 12 gauge wire or so.
Key point here......What would adding a proper ground elsewhere hurt? Nothing......
 
The reason im asking is i get low voltage around 13 volts in gear with alternator loaded. Alot of people say this is normal I don’t get how it normal. Is it putting more strain on the battery constantly charging discharging specially in city driving ?
 
13-13.5 volts should be about normal on a regular operation.

I think you need to learn what charges the Battery is amperes not voltage. When you have some amperes failure the voltage comes into a weird readings. That's why I preffer AMMETER before the voltimeter.

BTW, the regulator is grounded to the body, so another reason to get that ground strap


when I said my 74 got it, I meant FACTORY installed
 
13-13.5 volts should be about normal on a regular operation.

I think you need to learn what charges the Battery is amperes not voltage. When you have some amperes failure the voltage comes into a weird readings. That's why I preffer AMMETER before the voltimeter.

BTW, the regulator is grounded to the body, so another reason to get that ground strap


when I said my 74 got it, I meant FACTORY installed
I have both. So if ammeter doesn’t go to the discharge side im ok? Running a powermaster alternator.
 
if everything is correctly sourced and hooked, in good conditions you should be fine with centered ammeter reading. THAT'S in fact the goal! A centered reading on ammeter it means batt is in peace, neither being charged or discharged, and alternator is being able to source all the car requirements
 
if everything is correctly sourced and hooked, in good conditions you should be fine with centered ammeter reading. THAT'S in fact the goal! A centered reading on ammeter it means batt is in peace, neither being charged or discharged, and alternator is being able to source all the car requirements
That works for me thanks
 
Is there any advantages to adding a groud strap between the block and the firewall? Would it help alternator output? I noticed that they stopped using firewall grounds after 69 any idea why?
Most wire harness vendors typically recommend to ground battery to frame and block; block to frame; body to block/heads. Make sure you are not grounding to a painted / coated surface - needs to be clean bare metal. Grounds, especially in a older vehicle, are the most common electrical issue (aside from previous owner hack jobs). A reading of 12 - 14 is fine. Good luck.
 
Is there any advantages to adding a groud strap between the block and the firewall? Would it help alternator output? I noticed that they stopped using firewall grounds after 69 any idea why?

The regulator for one wire alternators on the firewall needed a current return path. That ground strap is the shortest path back to the alternator case if the alternator. Without it the return needs to find a way back through the body and the harness grounds to the alternator. That is typically a rather high current if the battery is charging hard. The electronic regulator and 2 wire alternator ran the field wire return back to the electronic box so that strap was not as necessary.
 
not sure If I really got what you said Jim... but I'm gonna post what I know...

Dual field alts get a full positive field from ign switch, hence the brush is isolated. Negative brush is not anymore full fielded like on earliers being directly attached to case, so then got the negative coming from regulator in regulated form to control the full magnetic fields into the alt. The electronic reg gets the full ground/negative from chassis to then feed the negative and regulated field throught its system to the alt through the green wire.

that is what I have allways known, maybe a bit off topic, but your post got me a bit confused.

( this is at a side of the ground strap, which my opinion is, if you don have it, add it. and my 74 got it from factory )
 
not sure If I really got what you said Jim... but I'm gonna post what I know...

Dual field alts get a full positive field from ign switch, hence the brush is isolated. Negative brush is not anymore full fielded like on earliers being directly attached to case, so then got the negative coming from regulator in regulated form to control the full magnetic fields into the alt. The electronic reg gets the full ground/negative from chassis to then feed the negative and regulated field throught its system to the alt through the green wire.

that is what I have allways known, maybe a bit off topic, but your post got me a bit confused.

( this is at a side of the ground strap, which my opinion is, if you don have it, add it. and my 74 got it from factory )

I think basically the same thing :)
 
My '71 had it and put it back on, using a new one, from block to the firewall. It wont and don't hurt. Making sure a proper ground helps in the long run.
 
I had and still have a firewall ground on my 73. It ensures that the frame and body are ground for all the items that use only that like speakers, radio and such.
 
Anyone have pics of the ground strap and what gauge wire should i use?
 
This is mine on my 73, still the original one that came with the car, still has the part number tag on it, its braded copper, so you could use an 8 gauge wire and be just fine.
DSC04781.JPG
 
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