Author Topic: Engine to firewall grounds  (Read 1771 times)

Offline rla98

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Engine to firewall grounds
« on: May 11, 2020, 03:03:32 PM »
Hello all!

I am new here. I have a 1976 Chevy K10 stepside shortbed. The engine compartment seems to be without grounding straps! (Shocking, I know)
I read through the forum and ordered three braided straps, one for the body and 2 for the motor as well as making one up for the battery to the radiator support.
As they say "a picture is worth a thousand words", so does anyone have a picture or diagram of where they go?
I am looking to keep it fairly stock.

Thanks!

R.L.

Offline ChrisD

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Re: Engine to firewall grounds
« Reply #1 on: May 14, 2020, 12:12:58 AM »
Hi,
I‘m sorry, if don‘t understand you right, but without grounding Straps, the motor isn‘t good running,
bacause it‘s relative isolated through  the rubber of engine and transmission mounts.
Then, you didn‘t wrote which engine you have, so I only can tell you, that with an i6 engine inside my car, 1 ground cable goes directly from batterie to the front chassis, and 1 bigger one (i don‘t know the us-size) from battery to the front passenger side of the engine under the ignition distributior.
I haven‘t a picture at the moment, but i try make one today.

Regards

chris
« Last Edit: May 14, 2020, 02:36:42 AM by ChrisD »
1978 Chevy C10 short bed with 250i6 and manual 3speed Saginaw
German us-car/truck newbie

Offline ChrisD

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Re: Engine to firewall grounds
« Reply #2 on: May 14, 2020, 05:34:08 AM »
Okay, made 3 pictures
Behind the battery
https://www.directupload.net/file/d/5819/p8mbewyt_jpg.htm
on the right frame - comes from the first point
https://www.directupload.net/file/d/5819/7yqub45q_jpg.htm
from battery to engine block
https://www.directupload.net/file/d/5819/maj4ilsu_jpg.htm

the red one, i think the truck also had a ground-problem, I'll do a bit copper paste on each point.

Regards

chris
1978 Chevy C10 short bed with 250i6 and manual 3speed Saginaw
German us-car/truck newbie

Offline rla98

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Re: Engine to firewall grounds
« Reply #3 on: May 17, 2020, 02:19:43 PM »
Thanks for all your efforts!   

Offline lilkiduno

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Re: Engine to firewall grounds
« Reply #4 on: May 28, 2020, 01:04:50 PM »
I believe bd did a great job listing the grounding locations and sizing needed.


Avoid star washers for ground connections and especially for battery cable connections.  Star washers can allow moisture intrusion to the connections, which exacerbates corrosion.  In addition, they decrease the surface area of direct metal contact.  Rather, burnish metal at the attachment site until it is bare, clean and shiny.  Make sure that ring terminals are properly sized to the bolt used to attach them.  Then liberally coat the terminal and attachment point with antioxidant during assembly. 

Never connect the engine-to-firewall ground strap to a valve cover bolt.  Attaching to a valve cover bolt will invite grounding trouble for all cab appliances.  Instead, attach the ground strap under a 3/8" bolt at the back of the passenger side cylinder head.

Whether you are experiencing electrical problems or refurbishing the vehicle, take an inventory of all of the vehicle grounds and service them appropriately (disassemble and clean connections to shiny bare metal, followed by liberally coating terminals and connections with moisture rejecting antioxidant paste).  Upon inspection you should discover the following vehicle grounds; recommended wire sizes are listed for any ground paths that need to be fabricated and installed:
  • battery-to-engine block or alternator bracket (2 gauge)  —  this is the primary high-current ground path (>150 amperes) for the engine and cab, supporting the full burden of the starter cranking current, charging system current and cabin electrical appliance current.  DO NOT attach the battery ground cable to an intake manifold bolt or stud!

  • battery-to-right (passenger side) frame rail (10 gauge)  —  this ground path is crucial as the primary extension of the main vehicle ground to the rear of the vehicle

  • battery-to-radiator support (10 gauge)  —  this is the primary ground path in support of all of the forward running lamps, forward turn signals, headlamps, and horn(s)

  • back of right cylinder head-to-cabin firewall (5/16" braided strap or 8 gauge)  —  this primary ground path ensures the cabin is adequately grounded in support of all cabin mounted interior and exterior electrical appliances

  • dash lighting and interior appliances-to-cabin left kick panel sheet metal (various, but typically 18 and 16 gauge)  —  this shared grounding point, common to nearly all of the electrical appliances inside the cab, interior lighting and instrument panel, is crucial to preventing the occurrence of floating grounds and associated electrical ghosts.

  • rear lamps-to-bed (16 gauge)  —  ensures the rear lamps are suitably grounded; alternatively, ground the rear lamps directly to the right frame rail

  • bed-to-right frame rail (14 gauge)  —  ensures the bed is suitably grounded in support of the rear lamps and other appliances grounded to the bed

  • cabin firewall-to-engine compartment hood (1/4" braided strap preferred for superior flexibility, otherwise 12 gauge, suitably located with sufficient length to allow opening and closing of the hood without catching, excessive flexing or stretching of the wire)  —  (optional yet highly recommended) helps manage radio "bzzzzzzz" and provides a stable ground for an optional hood mounted engine compartment lamp
Additional primary ground connections are okay.  If any of the recommended ground connections are missing, fabricate and install them!  If damaged, repair or replace them!


Other areas to check are the fusible links and harness connections at the starter and firewall junction block.  Loose connections or compromised fusible links can cause "mysterious symptoms."