Grounding block to chassis

[Anonymous]

I know some of you are thinking "duh" but according to the electrical diagram for my '66 Mustang, I should have a ground wire from my block to the chassis firewall. Here is the dumb question. Where is the best place to connect to wire to the engine? Head or bellhousing? Or does it really matter?

I have the negative lead from the battery connected to the alternator bracket but nothing to the chassis.


-Chris

 

[Guest]

Starter bolt

 

[MustangSix]

On my 66 there is a ground strap from the top starter bolt to the firewall just below the fan motor.

 

[Anonymous]

Great! Thanks guys.

But just to make sure I understand you...

-Chris

 

[MustangSix]

No, the ground strap is connected to one of the bolts that holds the starter to the engine block. The other end is attached directly to the firewall. The bolt you have circled is the power lug from the solenoid. Attaching the ground strap to that would be very interesting when you turn the key.,

 

[Anonymous]

Okay, that makes sense. But why would the illustration show the starter being ground that way? I mean it shows the power bung on the top of the starter (which is correct) but then a ground strap being attached to the front face of the starter. Shouldn't they show as you described? Why did they show this...(see circled part again)?


-Chris

P.S. not argueing but just wondering why they drew it this way.

 

[Anonymous]

as far as i know the starter motor is grounded through the bolts that attach it to the block. the thing you circled is not the power lug that comes from the solenoid, that is shown in your figure above. my guess was that the ground strap is there to ground the firewall not to ground the starter? when i put my starter on the only wire i connected to it was the one from the solenoid and it work just fine but i'm definitely going to put the ground strap in when i get a chance. i think they show this to make the full circuit clear. i'll look again tonight but i don't remember any other stud/nuts on my motor to attach the ground to. again i think it's just gounded through it's case to the block.

i was wondering the same thing as you when i was putting my 66 mustang back together. i couldn't figure out where on the firewall it was supposed to go.

 

[MustangSix]

Either way would work, but on most starters there isn't a separate bolt that you can hook a ground wire to. Normally there are only the two long screws that hold the case together, and there's no need to pull one of those out if you don't have to.

However, if there is a stud on the case like the drawing, and it's not a power feed, you could use that too.

 

[Anonymous]

Thanks again guys.

I'll run a ground from where the starter bolts to the bellhousing and then to the firewall. This way I will know for sure I have complete a circuit.



-Chris

 

[Anonymous]

on my maverick it was from one of the top bellhousing bolts to the firewall

 

[twentyover]

Doesn't hurt to have two grounds- one from the block to the chassis for starter support and a smaller one from the head to the chassis. The head/chassis ground is especially helpful on high rpm engines that run at large throttle settings, taxing the ignition.

Without this ground, you are banking on the head bolt transfering current from the head to the block. Knowing what the thread interface looks like on old head bolts (or at least my old head bolts), you might not want to trust that as a low resistance conducting path

 

[xctasy]

My XE Falcon ended up having three grounds.
One on the left rear bell housing,

one on the first right hand front side external bolt on the head, just above the alternator,

and a third on the alloy intake manifold.

Make sure you have really good quality wire. My wife found the alternator was showing red on the idiot light, so the auto shop spent an hour chasing the fault. They ended up placing a third wire on it, and the problem never surfaced again. The groundings are a common problem, especially on later cars as they went to a lower weight wire.

 

[Anonymous]

on my buddies maverick we ran an additional ground strap from the back valve cover bolt to the windshield wiper bolt on the firewall.

 

[kirkallen143]

Not butting in here, but all you need is from the battery (-) the the engine block (and there are a few tapped holes to choose from on the inline six), not the altenator bracket. From the location you chose, run another wire to the frame. The shorter the distance the better, and use at least 6 gauge wire, 4 gauge is even better.

Kirk ' 73 bronco

 

[Anonymous]

The Fairmont went to a braided ground cable from the back of the head to the firewall. There is also one from the Battery(-) connector to the right front fender, and the wiring diagram shows one from that wire (in the harness) to the left front fender. There is also a small spring plate (with a sharp, corrugated top edge) that is mounted to the firewall that grounds the hood to the firewall when the hood is closed. On older cars (i.e., a little rusty here & there), it is a good idea to run a 16-gauge wire (or bigger) from the (-) terminal of the battery to all of the above-mentioned places IN ADDITION to whatever you now have, as corrosion and age do create higher resistances over time.

 

[addo]

Mark, from my musicianhood I remember (tube amplifier) issues with "star" grounding vs point-point grounds as required. Sometimes, it seemed one held a better result than the other for no reason we could fathom. Voltages would be appearing the same, but one would be noisier, or tube bias wouldn't hold as long.

It's still something that bugs me with the automotive groundings. You talk about putting duplicate grounds everywhere essential. What if everything was star grounded to a terminal block near the battery? Would that be the ideal scenario? And what about the if the 8Ga and smaller wires were soldered with a high silver content solder, to the eyelets or spades? Just picking your informed brain.

Thanks, Adam.