grounding my heads

[ttocs]

I finally got time to finish this project and test it out. When it comes to grounds there are two rules, keep them as short as possible and ground everything at the same point. I had to find a balance between the two and made my cable a little longer then I might like to have them both grounded at the same point. I used the exhaust port bolt hole on the back of the head as the grounding point to the heads and then ran the cables up under my intake up to the front of the motor by the oil pressure sender to the motor ground.

To test if it did anything I hooked up my Ohm meter to the chassis ground and then to a spot that I sanded the oxidation off of above the header. When I didn't have them grounded I measured 24.7 ohms, after it was grounded I measured 16.4 ohms, so a reduction of 34%. It might add up to nothing, but I can't help but think a reduction that large would make a difference. At the cost of a little more weight being the only down side I am not sure why its not more common myself.

 

[96blak54]

Thats some good R&D there! Who'd thought.

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[duh09]

About the Holley system/power wire, I actually spoke with a rep on the Power Tour about their Sniper EFI and one thing they stressed over and over again was to hook straight from the battery. Their point was to keep the power pure and more constant. The fear from running closer to the alternator side had to do with ripple voltages, pulling from another point was the interference that could be caused by other things pulling on that circuit. They pretty much had a guy on call helping people with their EFI's at the stops and they told us most of the problems were simply power/ground wire issues or lack of a reliable fuel pump.

 

[ttocs]

Thats some good R&D there! Who'd thought.

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I think it makes sense at least it does to me.

About the Holley system/power wire, I actually spoke with a rep on the Power Tour about their Sniper EFI and one thing they stressed over and over again was to hook straight from the battery. Their point was to keep the power pure and more constant. The fear from running closer to the alternator side had to do with ripple voltages, pulling from another point was the interference that could be caused by other things pulling on that circuit. They pretty much had a guy on call helping people with their EFI's at the stops and they told us most of the problems were simply power/ground wire issues or lack of a reliable fuel pump.

that rep wasn't a big guy was it? I think with a car that normally has the battery up front it makes sense but with the batteries in the back, that power source now has a number of high current demanding amplifiers that can tap the power from the alt before it makes it to the batteries.

 

[evilcw311]

Il
I think with a car that normally has the battery up front it makes sense but with the batteries in the back, that power source now has a number of high current demanding amplifiers that can tap the power from the alt before it makes it to the batteries.

But at the same time, a battery is acting like a capacitor and filters put the ripple.


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[ttocs]

thats true but I still would prefer to have the holley power tapped closer to the alt, before the amps power point that will create the ripple. What your opinion on the head grounding?

 

[Grizzy]

I finally got time to finish this project and test it out. When it comes to grounds there are two rules, keep them as short as possible and ground everything at the same point. I had to find a balance between the two and made my cable a little longer then I might like to have them both grounded at the same point. I used the exhaust port bolt hole on the back of the head as the grounding point to the heads and then ran the cables up under my intake up to the front of the motor by the oil pressure sender to the motor ground.

To test if it did anything I hooked up my Ohm meter to the chassis ground and then to a spot that I sanded the oxidation off of above the header. When I didn't have them grounded I measured 24.7 ohms, after it was grounded I measured 16.4 ohms, so a reduction of 34%. It might add up to nothing, but I can't help but think a reduction that large would make a difference. At the cost of a little more weight being the only down side I am not sure why its not more common myself.

That seems like alot of resistence to me you should only have .5 ohm at the most if you have solid grounds. For me i dont want more then .2 ohms.

 

[ttocs]

ya know I thought the same but then I have never check ground resistance like this before or know of anyone that has to check my data. if you read how I tested it instead of testing directly between the two points I was attaching the ground wire, I measured between the head and the chassis ground rather then the head/motor ground. Yea sure they are all the same but they are all connected by feet of wire/metal. I had to scrape the powder coating I put on the alt case as well as on the back of the accessory bracket it mounts to so I could be sure the chassis of the alt was grounded. This alt being a HO competition version it has a ground and a power lug on top. I have a really thick ground strap that goes from the lug to the motor ground to be sure it is grounded, and a 0 awg ground wire going from the alts ground lug to the chassis ground where I measured from. I went back through and made sure they were all tight after these readings as they struck me as a bit high as well but like I said I am not measuring 12" of speaker wire there is a bit more in between.

 

[Grizzy]

The last LS swap I did at work I was able to test from the ground post on the battery to any bolt on the engine and had .2 ohms and the leads on my meter test at .1 ohm. Granted we use expensive wire and for battery cables we actually use welding lead because they handle a much higher amp load for gauge of wire. We also wire our cars like a fiberglass car and use a ground block to centralize all gorounds.

 

[ttocs]

I revisited this today as I had thought he was right they were too high from the time I measured them. I went back today and tested my grounds by giving a good pull on them was surprised that 2 of my grounds could wiggle, certainly not secure. So I tightened them up and now I am measureing 4 ohms at the heads, a significant drop from only being a little loose.

 

[evilcw311]

So your saying the guy who connected the grounds was slacking.....?!? ;-)


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[ttocs]

yup sure was. I have a bad habit of getting things finger tight and then leaving them with the intention of going over all the bolts now at the end. That was why I was on my back today under the car starting in the back of the car and working my way forward to test every nut/bolt I have touched to ensure they were tight. The grounds were still loose because it was a bitch to tighten them up where they were located.

 

[evilcw311]

Admitting you have a problem is the first step, come to slackaholics anonymous and we can help you with this!!! Lol


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[tech54K]

I didnt ground my heads separately but I have a 4/0 ground cable on the block. I used the back of my heads to provide ground to my coils and I havent had any issues. Running a cylinder head ground wouldnt be a bad idea (you already know that).

yes, I did the same thing.