Help with grounding...bolt size question

[Stang951]

The grounds on my 351W at the power steering/ac brackets isn't doing the job. I think because of all the paint and the aluminum the ground sucks so I am switching to the passenger side where there is a tab on the block right below the head, and one on the front of the engine, toward the timing gear. I can't seem to find the right size bolts for these two spots.

Anyone have any ideas what size these two bolts might be? I've been at this for two days now and I am pulling my hair out.

 

[jrichker]

Aluminum makes good ground material. The power compay uses aluminum wire to get the power to your house.
All grounds need to be clean and shiny. The ground down near the oil filter where the starter gound bolts is the best spot. The bolt is US coarse thread, either 5/16 or 3/8".

If you use an accessory bracket for a ground, there should be no paint between the aluminum bracket and the engine block where they bolt together.

 

[Stang951]

Thanks J. I tried a numerous amount of bolts and couldn't find one to fit. I was trying on the passenger side of the bloc, probably in a similar spot.

The block probably does have paint on it behind the brackets. I gave up a few hours ago and decided to relay the bricks in the back yard. Might try again tomorrow morning before I start BBQing.

 

[BlownFiveLiter]

I currently have the ground in my 95 attached to the engine mount. Works like a charm, and no hunting for bolts necessary!

 

[tmoss]

When I pulled my stock ground bolt out of the timing cover, most of the threads in the aluminum cover were corroded away. My starter was dragging and so I was checking out the circuit connections. The reason this happens is "galvanic corrosion" due to a steel bolt in the aluminum (dissimalr metals). The aluminum is less stable than than the steel (gives up ions easier) and so the aluminum literally corrodes away. I suggest using an electrical grease commonly reffered to as "No-Ox" that electricians use in aluminum cable connectors that connect to copper cable. It will help avoid this kind of problem. I switched my ground connection to the head rather than the timing cover.

 

[Stang951]

Didn't get a chance to play with it today. Maybe tomorrow.
Found a bolt that will fit all the way through the hole I was trying to mount it to. Now I need a nut, and I should have better ground in the engine compartment. I'll let everyone know how it turns out when I get finished.

 

[Stang951]

Got a chance to change the cables in the front, but the voltage is still bouncing a little, above 2500 rpms?? Moves a little at idle but not much, when the gas is goosed, there is a spike in the voltage and then it quickly drops to normal. Gonna check the grounds in the trunk and rear frame next.

Any other suggestions?

 

[tmoss]

If you have welded in subframes, ground the battery to the rear of the connectors and then take a cable from the front of the connector to the engine and fire wall.

 

[Stang951]

I may just run one to the front of the car. In all the years that I have been working on cars I was told that the ground should be kept to a maximum length of three feel, so I am leary of running a ground all the way to the front of the car.

Is it safe to run the ground under the car? I have the positive cables inside of the passenger compartment, and it's probably bad mo-jo to run them alongside each other.

 

[jrichker]

I may just run one to the front of the car. In all the years that I have been working on cars I was told that the ground should be kept to a maximum length of three feel, so I am leary of running a ground all the way to the front of the car.

Is it safe to run the ground under the car? I have the positive cables inside of the passenger compartment, and it's probably bad mo-jo to run them alongside each other.

Do you have a rear mounted battery?

 

[Stang951]

Yep! I thought that is just my problem, but I have heard of alot of other people that have no issues like this with the battery in the trunk.

 

[jrichker]

Rear mounted battery ground wiring. Follow this plan and you will have zero
ground problems.

One 1 gauge or 1/0 gauge wire from battery negative post to a clean shiny spot
on the chassis near the battery. Use a 5/16” bolt and bolt it down to make the
rear ground. Use a 1 gauge or 1/0 gauge wire from the rear ground bolt to a clean
shiny spot on the block.

One 4 gauge wire from the block where you connected the battery ground wire to
the chassis ground where the battery was mounted up front. Use a 5/16” bolt
and bolt down the 4 gauge engine to chassis ground, make sure that it the metal
around the bolt is clean & shiny. This is the alternator power ground.

The computer has a dedicated power ground wire with a cylindrical quick connect
(about 2 ½”long by 1” diameter. It comes out of the wiring harness near the
ignition coil & starter solenoid (or relay). Be sure to bolt it to the chassis ground
in the same place as you bolted the alternator power ground. This is an
absolute don’t overlook it item for EFI cars
Note: The quick disconnect may have fallen victim to damage or removal by
a previous owner. However, it is still of utmost importance that the black/green
wires have a high quality ground..

Picture courtesy timewarped1972

Crimp or even better, solder the lugs on the all the wire. The local auto stereo
shop will have them if the auto parts store doesn't. Use some heat shrink tubing
to cover the lugs and make things look nice.

For a battery cut off switch, see http://www.moroso.com/catalog/categorydisplay.asp?catcode=42225
is the switch http://www.moroso.com/catalog/images/74102_inst.pdf is the installation instructions.
Use the super duty switch and the following tech note to wire it and you will
be good to go.

Use the Moroso plan for the alternator wiring and you risk a fire. The 10
gauge wire they recommend is even less adequate that the stock Mustang
wiring.

There is a solution, but it will require about 40' of 18 gauge green wire.

Wire the battery to the two 1/2" posts as shown in the diagram.

The alternator requires a different approach. On the small alternator plug
there is a green wire. It is the sense lead that turns the regulator on when
the ignition switch is in the run position. Cut the green wire and solder the
40' of green wire between the two pieces. Use some heat shrink to cover the
splices. See http://fordfuelinjection.com/?p=7 for some excellent
help on soldering & using heat shrink tubing.

Run the green wire back to the Moroso switch and cut off the excess wire.
Try to run the green wire inside the car and protect it from getting cut or
chaffed. Crimp a 18 gauge ring terminal (red is 18 gauge color code for the crimp
on terminals) on each wire. Bolt one ring terminal to each of the 3/16" studs.
Do not add the jumper between the 1/2" stud and the 3/16" stud as shown it the
Moroso diagram.

How it works:
The green wire is the ignition on sense feed to the regulator. It supplies power
to the regulator when the ignition switch is in the run position. Turn the
Moroso switch to off, and the sense voltage goes away, the voltage
regulator shuts off and the alternator quits making power.

The fuse & wiring in the following diagram are for a 3G alternator. The stock alternator uses a dark green fuse link wire that connects to 2 black/orange wires. Always leave them connected to the starter solenoid even if you have a 3G alternator.

See the following website for some help from Tmoss (diagram designer)
& Stang&2Birds (website host) for help on 88-95 wiring
http://www.veryuseful.com/mustang/tech/engine/ Everyone should bookmark this site.

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

Complete computer, actuator & sensor wiring diagram for 88-91 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

 

[Stang951]

Thanks for all the info J. The only thing that I am missing from the first diagram is the ground all the way up to the block from the rear. I have two grounds from the battery, one to the chasis and one to the frame in the rear. In the front I have one from the block to the chasis and one to the sway bar mount at the frame.

I am running a Flaming River cut-off switch, and for the life of me right now I cannot remember how I ran the wiring from the alternator, but I am using 1 gauge wiring for power wires. I also am using 2 solenoids with a second switch on the ignition for the actual starter, since I upgraded to a newer style starter with a solenoid incorporated. I'll have to post some diagrams for the entire wiring system and let you take a look.

Part of my problem now is that my cabling supplier went out of business after Hurricane Katrina, and I don't want to spend a fortune on specialized audio power wires, so I have to hunt down another source for ground cable.

 

[jrichker]

Thanks for all the info J. The only thing that I am missing from the first diagram is the ground all the way up to the block from the rear. I have two grounds from the battery, one to the chasis and one to the frame in the rear. In the front I have one from the block to the chasis and one to the sway bar mount at the frame.

I am running a Flaming River cut-off switch, and for the life of me right now I cannot remember how I ran the wiring from the alternator, but I am using 1 gauge wiring for power wires. I also am using 2 solenoids with a second switch on the ignition for the actual starter, since I upgraded to a newer style starter with a solenoid incorporated. I'll have to post some diagrams for the entire wiring system and let you take a look.

Part of my problem now is that my cabling supplier went out of business after Hurricane Katrina, and I don't want to spend a fortune on specialized audio power wires, so I have to hunt down another source for ground cable.

Welding cable will do nicely, or see http://skycraftsurplus.com/ they have all kinds of wire and connectors and will have what you need. The wire can be found at http://skycraftsurplus.com/index.asp?PageAction=VIEWCATS&Category=24