Proper Grounding

[ATOLightning]

Need a little help from all the electrical folks out there...

I've read tons of posts on multiple car forums over the years and hardly any recommend the same thing.

Where's the best place to ground and how many grounds? I'm planning to use a Coyote crate engine with the Ford Engine Harness and the RF Chassis Harness. Some people say negative battery post to both the chassis and engine block, then to the heads and starter. Some people say not to ground the heads since they are mated to the block. Some say every headlight and tail light to the chassis and the chassis wire harness. Also the RF harness to the chassis via the dedicated ground wire on the harness near the fuses.

Some of that seems redundant. Essentially, my question is...Can you ground in too many places to the chassis? What's enough/too much.

Tips, Comments, Concerns are all welcome. So far I've just grounded the RF harness via the labeled ground wire IAW the manual. I don't want to drill holes everywhere in the chassis if they are needed:)

[68GT500MAN]

Bad grounds can cause many headaches later. That being said, I used a dedicated ground line from the front to the back with four places to attach grounds from the lights, gages etc. Steel is a very poor conductor of electricity compared to copper. A little more work for me during the build, but no problems with grounds later.
Doug

[frankeeski]

In answer to your question, no, you can't ground too much but at some point it just gets ridiculous. Here is what I did, and it works out well. Where ever you have a ground in the wiring harness make sure it goes to a welded post on the chassis, whether we are talking about the chassis harness, engine harness or dash harness. You will have to weld in the posts yourself or have someone who can weld them for you. I like to use a steel bolt for these. You could drill and tap the chassis, but I am not a fan of this approach, the threads rust after a while and tend to loose there continuity. For the battery use at least a #2 cable to ground the battery to the chassis, and again take it to a welded in stud. Ground the engine block to the chassis, here you can use a spot on the engine mount brackets. Again to a welded in post and I would add one from the chassis to one of the starter mounting bolts. The last thing I would suggest, is again, use at least #2 cable from the battery to the main power feed.

[CraigS]

I think grounding lights and horns and similiar to the frame is fine. All normal cars do it that way. But alternator,starter,battery need careful attention to be reliable. Now to the engine and efi-do too many grounds and that will be good. These don't need to be more than 12 ga wire but run a bunch. Both heads to intake,intake to block,block to battery (oops, this one is a 2ga),ecu to frame and block. The heads and intake are imporant because there are a bunch of sensors located on them. I am not a Coyote guy but Japanese efi runs mostly on 5 volts so it doesn't take much resistance to mess up a sensor reading getting to the ecu properly. This is why all the manufacturers went from 3 wire to 4 wire oxygen sensors. The 4th wire is a dedicated ground because just grounding through the exhause pipes wasn't effective enough over time.

[skullandbones]

ATO,

You can't over ground. Nice to know there are some absolutes in life! But seriously, the thing that sticks in my mind regarding EFI applications is what Ford Racing says which is: you can loss 3 percent performance in your engine from faulty sensor grounds. What CraigS said about the 5 volt readings is true. If you don't ground properly, the reading back to the computer will be less than optimal ( say 4.05 rather than 4.60 for maximum). Therefore, the computer will act accordingly and you loss something like amount of time injector stays open for fuel delivery. Therefore, I have a dedicated ground from the block to the computer, ground wire run from the battery to the bell housing, ground plates at the dash and near the battery in the truck with wires running directly to the battery. So everything except horn, lights don't run thru the chassis steel. It may seem like redundance but it's not really. Good luck, WEK.

[GJerry]

Breeze Automotive sells some really neat grounding bolts that work great and are easy to use. Just drill a hole in the frame where ever you want a ground as they are self tapping.

[Avalanche325]

Another rule for grounds is to make sure they are accessable when the car is completely assembled.