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Depends on what your doing. Are looking for a specific item you need to ground or the whole car? if it's the latter, You need more than one:yes: Battery to engine, engine to chassis, and battery to body. If it's a specific item, either should be fine as long as the car is grounded properly.
 

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Depends on what your doing. Are looking for a specific item you need to ground or the whole car? if it's the latter, You need more than one:yes: Battery to engine, engine to chassis, and battery to body. If it's a specific item, either should be fine as long as the car is grounded properly.
I have done a lot of big sterios in older cars and I have always done the same thing, I just double up on all the above connections and use larger wire.
 

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Discussion Starter #4
Depends on what your doing. Are looking for a specific item you need to ground or the whole car? if it's the latter, You need more than one:yes: Battery to engine, engine to chassis, and battery to body. If it's a specific item, either should be fine as long as the car is grounded properly.

The items I've got now are the Shiftworks in-dash tach and 3 2 5/8" Autometer gauges for the center console.

As of right now, I routed a 14 gauge wire from the engine ground to a bus bar underneath the dash so I don't have to run multiple wires back and forth thru the dash. The bus bar is split in 2 with power on one side and a negative ground (as mentioned earlier) on the other side.
http://www.perfprotech.com/dual-brass-bus-bar-11-fs40670/product/8461

What size wire should I use to ground the engine to chassis?

Would copper wire or stainless steel bonding strap be better for grounding?
 

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You need to have a good connection (as well as the proper size wire) between the battery negative terminal and the main sheet metal on the car. You also need another between the battery negative terminal and the engine block again of the proper size and having solid connections.

Some will say you also need a good connection added to what is said above between the engine block and the main sheet metal on the car but if the other two are correct then this probably isn't required.

What problems you can run into is let's say you have a ground wire from the battery negative terminal solidly connected and of the proper size connected to the front fender of the car and this fender is tightly mechanically bolted to the firewall. You then decide to ground things like your gauges, radio, or whatever to the firewall and then find out things might work properly or might not. The reason they may not work properly is even though the fender is metal as well as the firewall of the car, the mechanical connection between the fender and the firewall may not be good electrically.

Another reason you need good electrical connections is electricity will find the path of least resistance. Years ago I had a buddy fry his floor shifter cable and finally found out what was going on. The original battery negative terminal to the engine block failed but the battery negative terminal to fender connection stayed good. While trying to start the engine it found a ground through the shifter cable going from the transmission to the body of the car and then since the shifter cable could not handle the current/amperage it melted into a mess. Engines sit on rubber motor and transmission mounts and possible ground paths to the body of the car are though shifter linkages, speedometer cables, and emergency brake cables.

Jim
 

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The items I've got now are the Shiftworks in-dash tach and 3 2 5/8" Autometer gauges for the center console.

As of right now, I routed a 14 gauge wire from the engine ground to a bus bar underneath the dash so I don't have to run multiple wires back and forth thru the dash. The bus bar is split in 2 with power on one side and a negative ground (as mentioned earlier) on the other side.
http://www.perfprotech.com/dual-brass-bus-bar-11-fs40670/product/8461

What size wire should I use to ground the engine to chassis?

Would copper wire or stainless steel bonding strap be better for grounding?
I would use a grounding strap and these should be available at your local auto parts store. For your busbar ground, if your planning to run a bunch of grounds off of that I would go to a 10 gauge:yes: It might be overkill if your just hooking up grounds for instrument lights but your better off to be safe than sorry.
 

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Discussion Starter #11

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Well,

after searching the net and shopping at AutoZone, I found these for my 3 ground straps:

http://www.autozone.com/autozone/parts/Duralast-Battery-Cable/_/N-8gcx6?itemIdentifier=570475_0_0_

And from what you guys have said, 3 grounds will be needed.

1. Engine to chassis

2. Engine to firewall

3. Firewall to chassis

Along with the ground for the alternator to chassis ground which will be the 10 gauge wire.

Is there anything I missed??


Dan
I would be comfortable with the strap you linked from Autozone:yes: It shows that it's a #4 gauge which will handle about 90 amps. As custom Jim pointed out, make sure you have a good connection:yes: Every electrical circuit requires a return path for current flow and if you don't have a good ground for that it will take the least path of resistance (IE shifter cables, or anything else that has somewhat of a ground) Hope this helps.
 

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Good info Jim but, what size wire is needed????
Without knowing the current/amperage demands it's hard to say. It's like asking how big of a wire do I need to run to my home breaker panel and not knowing if the panel is just supplying a few lights or it's needing to power a hot tub, an electric furnace, water heaters, and so on.

If you know the current/amperage demands and know the lengths of the wires then there are online charts you can kick these figures into and they calculate the wire size. There is a relationship between having to go to a larger gauge wire the longer it becomes. These numbers might not be accurate but a foot of 10 gauge wire might handle 80A but if it it 15' long then it might only handle 30A.

Jim
 

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More grounds are always better. When weird stuff is happening it is generally due to a ground issue. Grounds should always be run as short a distance as possible.
Had a customer call and ask for new T3's for a Chevelle. I asked him what the problem was. He had a four headlight system. Told him its a ground issue. To check the grounds at the headlights. He said no way its the bulbs. I told him to spend 30 minutes checking. He did, the ground was loose. Saved himself the cost of new T3's.
Lesson here is that you cannot have enough grounds
 

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Discussion Starter #16
Could I use a bolt off of the transmission as a ground wire spot?

In my prior list, I've accomplished 2 out of 3.

1. Engine to chassis ** Done **

Found a bolt on the front part of the engine near the timing chain that is connected to the frame at one of the fuel line adel clamp bolt holes.

2. Engine to firewall


3. Firewall to chassis ** Done **

There's a stud for the emergency parking brake assembly that gets bolted to the firewall and I cleaned off the crud and put one of those 4 gauge wires on that stud and taped a hole on the frame for the other end of the connection.
I also found a spot on the passengers side where I was able to use a sheet metal screw and tied off a section of 10 gauge wire as another ground.


That's the reason for the question about the transmission bolts. I could use one of those to connect #2 on the list and the car will be complete with grounds.


BTW, I cleaned all the grounds to bare metal, coated with dielectric grease and top coated all with liquid tape. I will apply the 2nd coat tomorrow when all is done.

Dan
 

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Discussion Starter #17
Well,

to close out this chapter on my car, I selected a bolt off of the backside of the intake and ran it to a spot on the firewall with the last 4 gauge ground wire. I also drilled out a hole in the firewall for the ground needed for the HEI dizzy and the 2 grounds that will be comming off of the valve cover studs.

Hopefully, I've got enough ground wires that will not bother me in the future. Because, with this FAST system, I'm needing all the grounds possible..
 
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