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engine ground straps

Discussion in 'The Hokey Ass Message Board' started by andy 'lowlife inc.", Dec 10, 2008.

  1. andy 'lowlife inc."
    Joined: Jul 10, 2008
    Posts: 10

    andy 'lowlife inc."
    Member
    from santa cruz

    i have a 1953 chevy with a 350 sbc. i have heard from a few people that i should have 4 engine to body ground straps. any truth to this? i just put the engine in the car and am ready to do some testing, but want to make sure i'm doing everything right. i thought that two ground straps would be fine. (one from the passenger valve cover to the firewall, the other from the engine block to the inner fender well.) any thoughts and comments would be appreciated. this is my first build and i am trying to be patient and do it right.
    thanks
    andy
     
  2. plym49
    Joined: Aug 9, 2008
    Posts: 2,742

    plym49
    Member
    from Earth

    If by grounding to the valve cover you mean to sheet metal, I 'd suggest that you ground to a solid bolt, for example where your alternator bracket attaches to the block. Something heavy like that. Make sure you have good clean metal to metal contact.

    One ground between engine and frame is sufficient if it is good enough. Also, you want to ground it to the frame, not to the sheet metal of the car.

    Ever see a car try to crank with no engine to frame gound? Usually the throttle linkage or something like that starts smoking, because the starter current is finding its way to the frame wherever it can.
     
  3. Dirty2
    Joined: Jun 13, 2004
    Posts: 8,900

    Dirty2
    Member

    You need a ground from batt. to block , block to frame and block to body .
     
  4. dirtbag13
    Joined: Jun 16, 2008
    Posts: 2,522

    dirtbag13
    Member

    yeah i would say one good ground from a unused hole somewhere on the engine block to the frame , one from the battery to the engine, and one from the body to the frame shound be sufficient as long as you use quality terminals and have a clean grounding surface !
     
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  5. plym49
    Joined: Aug 9, 2008
    Posts: 2,742

    plym49
    Member
    from Earth

    Yes, but also depends on where the battery is mounted. Could be in the trunk; no need to run a ground cable all the way up front.

    The battery needs to be grounded to the frame OR the block with a heavy cable.

    The frame and the block need to be grounded to each other with the same-size cable.

    The body has plenty of places where it gets connected electrically to the frame, and starter current does not flow through the body (just minor accessories). So you don't usually require a frame to body ground cable, although one does not hurt. It does not have to be as big a gauge. Could be one of those little braided straps.
     
  6. Dirty2
    Joined: Jun 13, 2004
    Posts: 8,900

    Dirty2
    Member

    I used to always ground to the frame but its been proven that the frame is not a good conductor. I still do it tho.
     
  7. 36-3window
    Joined: Apr 10, 2002
    Posts: 10,846

    36-3window
    Member

    i always run the battery ground cable to the block , then grounding straps from that same spot on the block to the body and to the frame as dirty2 said
     
  8. phat rat
    Joined: Mar 18, 2001
    Posts: 3,492

    phat rat
    Member

    My cpe battery is in the trunk, so battery is grounded to frame, motor gounded to frame and body grounded to frame. Never had a problem yet with over 70,000 mi on it. Be sure all grounding spots are clean.
     
  9. thecockeyedwallaby
    Joined: Feb 27, 2007
    Posts: 262

    thecockeyedwallaby
    Member
    from Kelowna


    Why would you ground the valve cover? The valve cover never needs to complete a circuit does it?
     
  10. tommy
    Joined: Mar 3, 2001
    Posts: 14,735

    tommy
    Member

    The size of the ground will depend on how much amperage you are making it carry. You should only need 1 properly sized engine to body ground strap. If the battery is grounded to the frame (I don't recommend that) then you will need a ground strap from the engine to the frame as large as the battery cable for carrying the current necessary to start the car. (especially when the engine and starter are up to temp) Just remember that every mechanical connection in the starting circuit is a potential spot for corrosion and a bad connection. For my money, the fewer of them the better.

    If the battery is grounded to the block or trans then the ground strap from the engine to the body only has to be big enough to carry the amperage of the lights, and all accessories. For most of our type cars with 12Vs it really doesn't need to be too big. The factory one on my 56 Ford is about a 10-12 ga. from the engine to the firewall. I have a personal fetish for the uninsulated braided copper ground straps just because I think they are a cool old looking detail. Some of them come with serrated lugs that promote good contact.
     
  11. PRIMERDAVE
    Joined: Jun 8, 2005
    Posts: 895

    PRIMERDAVE
    Member

    your correct the valve cover doesn't need to complete a circuit....but if you look at mid 60's GM products that is how they grounded....batt to block, body to valve covers
     
  12. rustyford40
    Joined: Nov 20, 2007
    Posts: 2,170

    rustyford40
    Member
    from Mass Bay

    I ground from the starter to the frame. The starter draws the most amps.
     
  13. Fat Hack
    Joined: Nov 30, 2002
    Posts: 7,716

    Fat Hack
    Member
    from Detroit

    One neat thing about automotive electrical wiring is that there's no such thing as "too good of a ground"! A good ground wire strategy makes for a happy electrical system...you'll use less current to operate various components since resistance will be lower and things like dim bulbs will be oddities that OTHER people chase after!

    I tend to "over-ground" a car when I wire it, but I like everything to work trouble-free! My general rule is to treat every car as if it's a fiberglass car! Simply put, that means thta each component gets it's own ground wire, even if it happens to be grounded to a metal body already!

    To start with, I run a good battery ground cable from the negative post to the engine. The closer you can bolt the ground cable end to your starter, the better. I typically try to use an extended bellhousing bolt, or if that is not an option, then I try for a motor mount bolt or other good 3/8" bolt hole on the block, heads or intake manifold somewhere.

    From there, I like to get a Ford style 'switch to starter' battery cable (with black insulation)...this is a battery cable with heavy 'eyelet' on each end. I "piggyback" one end of that towhere the negative battery cable is bolted to the engine so that they physically touch each other, then connect the other end of it to the firewall with a long stud accessible from inside the car as well as under the hood. Elsewhere on the engine, I'll often run another switch-to-starter type cable from the block to the frame. That way, your engine, frame and body are all, in effect, connected right to your negative battery post!

    When wiring up things like lights, stereos, etc...I'm normally making a taped harness especially for them anyhow, so I just add one more 14, 12 or 10 gauge black wire to the harness to serve as a dedicated ground wire for that component. In the case of things such as tail lights, the housing is often the ground, just by touching metal on the body...but I'll connect my new ground wire to the socket or base just to be sure! On headlights, I run a dedicated ground wire to each one and it goes into the headlight harness as well.

    Remember that long stud on the firewall that's accesible from under the dash? That's where I connect all the ground wires I've run through the various harnesses to the different components using round eyelet connectors. This is as good as grounding each component directly to the battery, and eliminates a lot of potential electrical gremlins down the road. All bulbs burn bright, the headlights draw less current, and there's never a ground issue...even on old rustbuckets!

    (In some cases, where the negative battery cable has that little extra 10 guage black wire hangin off of it, I'll use that as the headlight ground, but otherwise, it goes to that "ground stud" like everything else).

    No excuse for bad grounds...just wire 'em all as if they were fiberglass!
     
  14. SlamIam
    Joined: Oct 8, 2007
    Posts: 366

    SlamIam
    ALLIANCE MEMBER

    Best if the negative cable from the battery attaches to the block at the starter, and the frame and body are then grounded separately to that same point with heavy conductors. If the frame is the negative return for the battery, the ground cable from the frame to the block needs to be as large as battery cable. A 10-gauge ground is usually sufficient for the body. Bad grounds can cause really weird problems that can be hard to diagnose. A badly grounded block can mess with electronic ignition, even causing it to fail. This happens because large current devices like starters, alternators, and a/c compressor clutches need a very low resistance path back to the negative terminal of the battery, and will seek one anywhere they can find it if a direct path is not provided. If you want to test the quality of your engine ground, attach the negative lead of a voltmeter to the negative terminal of the battery, attach the positive lead of the voltmeter to the engine block, and watch the voltmeter as you crank the starter. It should register less than a volt if the block is properly grounded. One big no-no: never attach a ground from headlights, a fan or a horn near the radiator. The ground currents from these heavy load devices can cause electrolysis problems in the cooling system that eat aluminum.
     
    Last edited: Dec 11, 2008
  15. RacerRick
    Joined: May 16, 2005
    Posts: 2,742

    RacerRick
    Member

    I aways run a heavy ground strap from one of the starter bolts to the frame, as well as having the battery ground go to both the engine and frame.

    Starter spins much faster.

    What sucks is when you have a perfectly good looking cable that has serious internal corrosion. That can be a hair pulling experience.
     
  16. plym49
    Joined: Aug 9, 2008
    Posts: 2,742

    plym49
    Member
    from Earth

    ??? The frame is solid steel. It has a far greater current carrying capacity than the largest cable you would see on a car. Compare cross-sectional areas..............

    If, though, the CONNECTION to the frame is not good, then that will work as badly as any other bad conenction.
     
  17. 36-3window
    Joined: Apr 10, 2002
    Posts: 10,846

    36-3window
    Member

    you can debate grounding the - side of the battery to the engine block VS the frame , and both will have valid reasons... and both may be right , and work just fine

    i prefer grounding the battery right to the engine block..i have my reasons , the best one is i think it works better. i know what works for me , your experience may vary
     
  18. 29nash
    Joined: Nov 6, 2008
    Posts: 4,547

    29nash
    BANNED
    from colorado

    You just said that to see if anybody was paying attention.:D
     
  19. TagMan
    Joined: Dec 12, 2002
    Posts: 4,534

    TagMan
    ALLIANCE MEMBER



    Works OK if you take the paint off your connection point.......:rolleyes:
     
  20. power58
    Joined: Sep 7, 2008
    Posts: 430

    power58
    Member

    Another good Idea for grounding came from Circle Track Mag. Put a braided Ground strap from the left cylinder head to the firewall and a braided ground strap from the right cylinder head to the firewall. With thread sealers and special head gaskets the plugs might foul without the head ground straps. The Guy in the Circle Track article was fouling the 4 plugs on the right head. The ground straps fixed the problem. and as said before you can never have too many grounds. Grounding, it's not just for starting anymore.
     
  21. gashog
    Joined: Dec 9, 2005
    Posts: 918

    gashog
    Member

    If you're going to ground the starter to the battery through the frame, it's a good idea to use a common rail and star washers on the bolts. Alot of the issues with frame grounds are the result of the electrical path depending on the mechanical connection of old riveted joints in the sections of the frame.
     
    Last edited: Dec 12, 2008
  22. CraigR
    Joined: Jun 20, 2008
    Posts: 398

    CraigR
    Member
    from California

    I've seen starting issues go away by runnin a ground all the way from the trunk mounted battery to the starter. Yes they had good frame grounds before, and it don't completely make sense to me either, but I've done everthing that way since. You just can't beat grounding the battery to the starter.
    Flipside is I've had vehicles with the ground from battery to frame, frame to engine, no problems. But if you do have problems, that'd be the first thing to check.
    Like FAT HACK says, there's no such thing as too good of a ground.
     
  23. THESNEAKYTIKI
    Joined: Jun 10, 2005
    Posts: 127

    THESNEAKYTIKI
    Member

    Here is a pic of my engine ground strap on my 55 wagon. The battery is located in the trunk. The battery is grounded to a bolt welded to the frame rail at the back of the car. The motor is grounded from the starter bolt to a bolt welded to the top of the front of my frame. The same ground that is on the top of the frame is looped to a ground that goes to the floor of the car which is connected to every ground inside the car. Your motor should be good with one good clean ground. The point is as long as your grounds are good you will have a good circut. Make sure to clean the metal your ground is attaching to. Hope this helps. thesneakytiki

    [​IMG]
     
  24. stagernwings
    Joined: Dec 9, 2007
    Posts: 187

    stagernwings
    Member
    from tx

    Just a point of interest , dodge found that transmission tail shaft leaks were from electrical draws from the engine to the frame by way of the drive shaft . The metal to babit bushing would be so clean that an arc would destroy the seal and cause a leak .The fix would be to run a ground from the rear of the head to the fire wall were most other grounds would likely end up ie the dash, and one ground from the frame to body .millions of cars were built this way .c
     
  25. stagernwings
    Joined: Dec 9, 2007
    Posts: 187

    stagernwings
    Member
    from tx

    I have noticed that many cars here have batteries in the trunk . I think from old school drag racing when cars had skinny rear tires and needed transfer .What just kills me is people still do this with no good reason . a trunk is just bad design .c
     
  26. 32SEDAN
    Joined: Jul 30, 2008
    Posts: 1,200

    32SEDAN
    Member

    I did it to hide it. Last car I mounted it underneath on the frame rail on it's side (optima). Good reason for me.
     
  27. thecockeyedwallaby
    Joined: Feb 27, 2007
    Posts: 262

    thecockeyedwallaby
    Member
    from Kelowna

    I read an article stating that the voltage drop across a frame or body is actually fairly large, because the resistance is quite high. I think if you measured the resistance across the frame or body, you might be surprised. There's no sustitute for a good cable. Totally different material which lends itself far better for carrying a current.
     
  28. phat rat
    Joined: Mar 18, 2001
    Posts: 3,492

    phat rat
    Member


    I'd say you were wrong. I believe room is the biggest reason. As long as you pay attention to detail there's nothing wrong with it being there.
     
  29. Fat Hack
    Joined: Nov 30, 2002
    Posts: 7,716

    Fat Hack
    Member
    from Detroit

    I agree. I had a trunk-mounted battery in my old Mustang II with the 351W...the cramped engine compartment made battery space almost nill, so I moved it to the trunk (it was a Ghia coupe). People balked at it...saying it would create starting and charging issues, but that never happened. In fact, I stored the car all winter without touching it or putting a charger on the battery, and it fired right up a few months later.

    If you mount it securely, enclose it in a proper battery box, vent that box to the outside, run adequate cables and of course enough battery to do the job...there's no problems whatsoever!
     
  30. flathead daddy
    Joined: Jul 20, 2005
    Posts: 53

    flathead daddy
    Member

    Only extra advice is wherever you are connecting the ground straps to, you gotta scrape the pretty paint away from the connection area. I just fixed a starting issue on my friend's rod, because he painted his motor all pretty, frame was powdercoated, etc, but he was depending on the threads of the screws to make the ground- no good.

    What we did was to scrape enough of the paint away so that we knew the ground connection was metal to metal (very carefully, of course) then reconnect the ground wire from the bellhousing where the starter was attached to the frame (the negative from the battery was also connected to the frame at a different spot, so we had to do the same thing there), then we touched up the paint where needed and magic! The starting issue was solved.....

    Although I guess I should have led him on that it was his optima battery so that I could have the "bad one"! He He...
     
    Last edited: Dec 12, 2008

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