Fred SS

iTrader: (3)

I recently saw an old post from a member that said it is not a good idea to ground your battery to the serpentine bracket. Can someone tell me why. I have had it that way for a few years now on my TPI swap. There is a flat spot I found on the engine block about 2 inches forward of the motor mount that I could use for the ground attachment.

OrangeBird

iTrader: (1)

Fred SS

iTrader: (3)

Thanks OrangeBird. Makes allot of sense. I'll use the flat spot I found on the block. Cleaned the paint off of coarse.

TTOP350

iTrader: (8)

For what its worth, the factory ran the ground to the lower driver side serp bracket mount bolt on the 88-92 birds.

Fred SS

iTrader: (3)

Thanks TTOP, I was wondering where the factory ran the ground. On my 350, there is a flat boss about 2 inches forward of the driver's side motor mount with a 3/8-16 tapped hole. I installed the ground there.

QwkTrip

iTrader: (22)

You did good. Best practice is to put the ring terminal directly against the object you want to ground, which is the engine block in this case. The bolt is only there to clamp the ring terminal against the engine block.

​​​​I think aluminum is a better conductor than iron, by the way

TTOP350

iTrader: (8)

I did a crazy google thing and found this..

Material IACS (International Annealed Copper Standard)
Ranking Metal % Conductivity*
1 Silver (Pure) 105%
2 Copper 100%
3 Gold (Pure) 70%
4 Aluminum 61%
5 Brass 28%
6 Zinc 27%
7 Nickel 22%
8 Iron (Pure) 17%
9 Tin 15%
10 Phosphor Bronze 15%
11 Steel (Stainless included) 3-15%
12 Lead (Pure) 7%
13 Nickel Aluminum Bronze 7%

* Conductivity ratings are expressed as a relative measurement to copper. A 100% rating does not indicate no resistance.

ULTM8Z

Yeah, I had my ground on the serp bracket a long time ago. Discovered while watching the engine during the dark, the ground was so bad, spark energy was literally jumping out of the plug wires and finding an easier path to ground by arcing out to nearby metal.

I actually ground to the cylinder head directly from the battery and the chassis. Then have another ground from that head to the other head.

OrangeBird

iTrader: (1)

I think I'll still leave my ground bolted to the iron block .....

Fred SS

iTrader: (3)

Thanks TTop for that information. I always knew silver was a slightly better conductor than copper, but I did not know iron was less conductive than alum and alum is less conductive than copper.


ULTM8Z, I plan to run a ground, copper wire, from the block to the cylinder head. I already have a ground connecting both cylinder heads. The ecm grounds are on the rear of the passenger side cylinder head. I have a heavy gage wire running from the passenger side head to the driver's side head.

Tibo

iTrader: (15)

Best way to ground the long block will be to ground the engine block and each head separately to their own individual grounding locations on a frame rail. The problem with grounding the heads together and then grounding only one head is that the head that is receiving the ground path from the other head will be much more noisy and the grounding wire will need to be bigger. The other problem with grounding multiple objects from the same point is not using a thick enough single wire. Another point to remember is that the intake, heads and block are only lightly grounded together. Because of the gaskets and thread sealer there is added resistance for a ground. If you don't ground the block well you can get starter problems and if you don't ground the heads you can get ignition issues. Another important grounding aspect nearly everyone forgets is the alternator round path. The alternator grounds to a bracket that grounds to a head that must ground to the frame or battery. So the connections between the alternator and brackets and then the brackets to block must be clean and unpainted. The grounding wire from the head with the alternator should also be a gauge heavier than the ground on the other head since it is carrying more of a load.

I never realized how electrically noisy our engines were until I installed my MegaSquirt. The engine ran horribly. I traced it down to the adjustable noise filter in MegaSquirt needing to be increased to cope with all the electrical noise.