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Discussion Starter · #1 ·
Is my '71 supposed to have a direct ground from the block to the firewall? If so, would not having one cause things like random dieseling at shutoff? Thanks.
 

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Yes it should have a ground from the block to the firewall. It is my understanding that most all cars have this arrangement. It is usually a flat "braided" cable. Not having an engine ground can causle all kinds of strange problems.

Hope this helps!
 

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No, lack of ground will not cause dieseling or run-on. For that matter nor will timing. When you turn the key off there is no ignition so timing is irrevalent. Things that will cause run-on are high idle, hot engine, carbon build up, stuck a/c idle up solenoid, faulty fuel cut relay where applicable.
 

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The two ground straps are not intended to carry current or to provide engine or body ground. Their function is to help suppress radio noise. The engine ground is provided by the negative battery cable that connects to the alternator bracket/engine.
 

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Where are the best places to hook grounds on the car? I was thinking Battery to alternatro bracket for sure. Then, where on teh firewall do we hook the strap to and where from engine? Do we need another strap to the frame? Thanks

Tony
 

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They won't fix any problem with the car, expect radio noise. I don't have them and don't plan to add them. Mine will run-on if the Idle Stop Solenoid isn't working and I've adjusted the idle up.
 

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When I went to start my wagon for the first time, this engine came from my truck and had a mini starter on it, and it would sing. Well anyway I went to crank the wagon and it was slow to start singing. I said to myself whats up with that. I checked my connections, blah, blah, could not find anything. So I decided to run a ground off the back of the block to the frame via firewall etc., now the starter is singing again. I also noticed my charging volts were higher etc. I know some will say something about bad grounds , loose connections etc. I believe in grounding. I have no noise in my radio, even when I have my CB on, I am running a modulator,amp etc. with this thing and everything is very well grounded. I don't get talking in my stereo from it. I have more grounds in this wagon than the ground has ground. I say ground it! It won't hurt, all it can do is help. Aircraft have lots of grounds, they are for noise, lightning, static discharge and everything else.
 

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Originally posted by Patrick O'Rourke:
So I decided to run a ground off the back of the block to the frame via firewall etc., now the starter is singing again.
Your original problem still exists. Since the starter works better now, the original problem is a bad negative cable or a poor connection on the block. My guess would be a cable problem since some of the interior items improved by sharing the 2 ground wires from battery (-).
The starter only needs the large negative cable for a return line. The problem was "fixed" by adding a second starter return line via the ground straps. When (or if) the negative cable problem worsens, the smaller ground straps will try to carry all the current to the starter motor. At that time, the smaller wire gage ground wire, tied to the right inside fender. will burn.
 

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A few years back a friend replaced the engine in his 85 Suburban. After completing the swap the starter motor ran slow. He got and installed a new starter, same thing. He took the new starter back exchanged it for another new starter. Same thing slow cranking. When I stopped by, to get the 350 4 bolt that he took out, he asked me about the slow cranking. The problem was when he removed the ground cable from the old engine he reattached it to the frame, thinking that there would be no need to deal with it when reinstalling the new engine. Needless to say after connecting the battery ground back on the engine the starter worked fine.

The point is the battery is grounded to the engine using the #4 ga battery cable and is all it needs to satisfy electrical needs of the engine. The small braded grounds are part of the radio equipment and are intended for noise suppression, not to complete any electrical circuits.
 

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WHen i got my cra back together i had a big problem of needing either a battery charger or someone to give me a jump to get my car to turn over, brand new everything. Had the big ground to the engine block, and thats it. The battery was charged, it just needed a little more over the hump oomf to get it actually turning over. My dad kept askin me if i has a ground from the engine to firewall and i just said no, thinkin that couldnt ever solve my problem. One day he came home with a strap and told me to put it on, so i did. And guess what? instantly everything works perfect. I proceeded to add an extra, and the electricals in my car have never been better.
 

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Just thinking out loud here, but what about looking at it from the other direction, where the ground cable is providing a solid ground for the body of the car. If the body has minimal contact with the frame/engine, there would be a weak ground for everything grounded to the body. The engine, has the neg. battery cable, and grounds to the frame pretty well, but other than the body bolts, what does the body have? It's isolated by rubber mounts, isn't it? The bolts usually get pretty corroded after a few decades too. I don't know about the rest of you, but I'll toss a ground wherever convenient, and look at it as a little extra insurance to keep 0V at 0V.
 

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Grounds are your friend, and cables are cheap, even at Auto Zone.
 

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I wondered about ground straps in the past, too. As I learned from John Muha, there is supposed to be a "pigtail" wire from the battery ground cable to the fender. Mine was there but it wasn't connected. After I connected it things worked alot better. This is the body ground connection.
 

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Discussion Starter · #15 ·
Hate to bring this up again because I want to confirm (since I actually have a radio problem as well) that I should have an engine->firewall groundstrap. Does it connect to a valve cover bolt or under an intake bolt or something? Will one suffice or would two be optimal? Thanks.
 

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Originally posted by soccerguy045:
Hate to bring this up again because I want to confirm (since I actually have a radio problem as well) that I should have an engine->firewall groundstrap. Does it connect to a valve cover bolt or under an intake bolt or something? Will one suffice or would two be optimal? Thanks.
Should have a strap on both sides. Firewall to Valve cover or cyl. head.
 

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Originally posted by John_Muha:
They won't fix any problem with the car, expect radio noise. I don't have them and don't plan to add them. Mine will run-on if the Idle Stop Solenoid isn't working and I've adjusted the idle up.
Might want to get 'em on there John. I've heard that failure to have the engine grounded properly can result in coolant electrolysis. What you end up with is charged coolant looking for a ground. Electrolysis can eat a heater core in short order.
 

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Originally posted by TimC:
</font><blockquote>quote:</font><hr />Originally posted by John_Muha:
They won't fix any problem with the car, expect radio noise. I don't have them and don't plan to add them. Mine will run-on if the Idle Stop Solenoid isn't working and I've adjusted the idle up.
Might want to get 'em on there John. I've heard that failure to have the engine grounded properly can result in coolant electrolysis. What you end up with is charged coolant looking for a ground. Electrolysis can eat a heater core in short order. </font>[/QUOTE]My engine is grounded to battery (-) and so is the sheetmetal. I doubt the voltage differetial between them is high enough to cause electrolysis. They are not needed. Took 25 years before the last core gave out.
BTW
The right head was also damaged the same way as the left.
 
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