hey how are you, i was wounding how many grounds and where to put them on an engine. At the moment i have one ground cable from the battery to my aluminum head. and one ground from the battery to the fender. (its a 86 Monte ss By the way, 357 sb)
PiperDavid14
A framed car gets a line from the negative battery to the motor, motor to frame and frame to body. A unibody car gets a line from the negative battery to the motor and motor to body.
I'll tell you how I do it, you do it as you wish. I make up my own lines from #4 battery cable cut to length, then sweat on copper lugs and cover them with heat shrink.
Battery negative to motor: There will almost always be a threaded hole somewhere on the block or head. If not, use a bolt that holds something else and is handy. Run a finishing tap down to the bottom of the hole and blow out the chips and other crud in the hole by spraying carb cleaner into the hole with the little red straw that comes with the can. Watch your eyes and do not breathe the vapor. Now, use a file or your pocket knife or other suitable tool to scrape off all crud, paint, rust, etc. from around the hole. You want the lug laying against bare metal when you tighten the bolt down. Cover the entire connection with clear silicone so that no moisture can get into it.
Motor to frame: Same way, but with a plain lug on each end of the cable. If there is not hole in the frame to use that's convenient, drill the proper size hole for a self-threading bolt. Make sure there are no fluid or electrical lines running inside the framerail that would be breached by drilling a hole. You don't have to push the drill bit all the way in, just stop when you feel the bit clear the metal on the other side of the rail. Use a file or knife or sandpaper to make a large, clean, bare spot of shiny metal to attach your lug to, then seal it as above.
Motor to body or frame to body: Find a place on the firewall where there is already a hole that you will have access to from the outside and from the inside of the car. If there is not one available, then look around for a good spot. You will want a spot on the inside where you can get to it with a socket or wrench to hold a bolt head. We're going to use a bolt and nut and maybe a couple of washers for this one. On the motor side, clean off an area down to bare, shiny metal where the lug will sit so that the lug will not be sitting on any painted part of the firewall. Run the bolt into the hole from inside the car and have a buddy attach the ground cable/washer/nut and tighten it while you hold the bolt head from inside. Once tightened, cover the connection thoroughly on the inside and the outside with clear silicone.
I'll tell you how I do it, you do it as you wish. I make up my own lines from #4 battery cable cut to length, then sweat on copper lugs and cover them with heat shrink.
Battery negative to motor: There will almost always be a threaded hole somewhere on the block or head. If not, use a bolt that holds something else and is handy. Run a finishing tap down to the bottom of the hole and blow out the chips and other crud in the hole by spraying carb cleaner into the hole with the little red straw that comes with the can. Watch your eyes and do not breathe the vapor. Now, use a file or your pocket knife or other suitable tool to scrape off all crud, paint, rust, etc. from around the hole. You want the lug laying against bare metal when you tighten the bolt down. Cover the entire connection with clear silicone so that no moisture can get into it.
Motor to frame: Same way, but with a plain lug on each end of the cable. If there is not hole in the frame to use that's convenient, drill the proper size hole for a self-threading bolt. Make sure there are no fluid or electrical lines running inside the framerail that would be breached by drilling a hole. You don't have to push the drill bit all the way in, just stop when you feel the bit clear the metal on the other side of the rail. Use a file or knife or sandpaper to make a large, clean, bare spot of shiny metal to attach your lug to, then seal it as above.
Motor to body or frame to body: Find a place on the firewall where there is already a hole that you will have access to from the outside and from the inside of the car. If there is not one available, then look around for a good spot. You will want a spot on the inside where you can get to it with a socket or wrench to hold a bolt head. We're going to use a bolt and nut and maybe a couple of washers for this one. On the motor side, clean off an area down to bare, shiny metal where the lug will sit so that the lug will not be sitting on any painted part of the firewall. Run the bolt into the hole from inside the car and have a buddy attach the ground cable/washer/nut and tighten it while you hold the bolt head from inside. Once tightened, cover the connection thoroughly on the inside and the outside with clear silicone.
yep, you can't have too many grounds 
For a good solid ground, here is what I do. I buy a side post battery converter - one of those posts that is supposed to screw into a side post battery and has the big lead post on it. Drill and tap the frame beside the engine for that post. Then put one of these from an accessory bolt to the frame. Dead reliable.
![Image]()
For a good solid ground, here is what I do. I buy a side post battery converter - one of those posts that is supposed to screw into a side post battery and has the big lead post on it. Drill and tap the frame beside the engine for that post. Then put one of these from an accessory bolt to the frame. Dead reliable.
Link please!curtis73 said:yep, you can't have too many grounds
For a good solid ground, here is what I do. I buy a side post battery converter - one of those posts that is supposed to screw into a side post battery and has the big lead post on it. Drill and tap the frame beside the engine for that post. Then put one of these from an accessory bolt to the frame. Dead reliable.
![Image]()
Since my ride is 'plastic' grounds are number one priority. I have battery to frame ground right at the battery. A big one like the picture.
Then the block and aluminum heads are both grounded together, the blower manifold and block are grounded together. Then there is a big ground strap from the block to the frame. All grounds are ground clean then bolted down.
I have 4 large ground terminal blocks in strategic locations on the body. These have 10 ga wire directly to the frame, again on a fresh clean spot. I service all frame connections in the early spring.
The ignition MSD has it's own hot side and ground wires directly to the battery except for the switch control.
You get bit by the 'ground syndrome' only once on these cars.
BTW, aluminum gets surface oxidation which begins immediately after cleaning and gets thicker with age. This is an excellent insulator. So is anodizing which is colored oxidation. I would not use a main ground on aluminum. This is why we work so hard to clean aluminum right before TIG welding....get rid of the oxidation as much as possible.
Ground to the block.
Then the block and aluminum heads are both grounded together, the blower manifold and block are grounded together. Then there is a big ground strap from the block to the frame. All grounds are ground clean then bolted down.
I have 4 large ground terminal blocks in strategic locations on the body. These have 10 ga wire directly to the frame, again on a fresh clean spot. I service all frame connections in the early spring.
The ignition MSD has it's own hot side and ground wires directly to the battery except for the switch control.
You get bit by the 'ground syndrome' only once on these cars.
BTW, aluminum gets surface oxidation which begins immediately after cleaning and gets thicker with age. This is an excellent insulator. So is anodizing which is colored oxidation. I would not use a main ground on aluminum. This is why we work so hard to clean aluminum right before TIG welding....get rid of the oxidation as much as possible.
Ground to the block.
NAPA Balkamp #770-6119
These ground straps are especially suited for grounding things like hoods, trunk lids, tailgates / liftgates ... etc. Anything with hinges.
You'll also see a couple more between the frame and my pickup box and the rad support. Rubber mounts are poor conductors as well.
Even for my after market steel car I have "several" dedicated grounds. One direct from the battery to the engine, then another from the engine to the chassis (these are like the woven ground cables shown above) then a third from the engine to the body and another (fourth) to the fuse panel which is for the gauges. Then there is the ground from the gas sender to the chassis and another for the MSD. The lights all have separate grounds to the chassis - tail, cowl and head lights. The trunk lift has a separate ground to the body. Probably more. The heavier gauge they are along with good bolts the better the connection/ground (I used some brass bolts plus some anti corrosion dielectric grease along with star lock washers too)
Dave W
Dave W
I would also add a ground from a transmission pan bolt to the body. A strap like pictured by 66GMC is ideal. Transmission shops buy these straps by the box and most consider a transmission ground on cars like yours mandatory. I've had it proven to me that older GM vehicles in particular need such a ground. I know a transmission rebuilder who doesn't need to see the car, if it had poor grounding to the transmission he can tell just by the electrolytic damage to the transmission bushings. Such bushing damage is well known to the transmission rebuilding industry.
GypsyR said:
You mean something like these - 2 of my several grounds before the body went on
:
yes, but only because I put some dielectric grease on the threads.techinspector1 said:
Thanks for the kindness. The sponsoring thought for that idea came from when I dropped a Caddy 500 in my 66 Bonneville. I forgot the engine ground and it cranked really slowly. About the time it quit cranking there were massive amounts of smoke coming from the firewall area.
Turns out, my Lokar tranny dipstick was attempting to ground the whole thing.
I went a little overboard on grounding it the next time
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