Grounding to aluminum head?

I always move the batteries to the trunk in my cars and run two #1 copper cables full length to the starter and ground location. I have grounded to the head boss on my aluminum heads and when freshening up the engine after 7 years, I noticed that the water passages in the heads, showed some signs of electrolysis, not bad, but more than I would have expected for as little the car is used. This is an iron block/aluminum headed 528 Hemi. Should I be attaching the ground cable to the iron block instead of the heads? Does grounding thru the head aggravate the electrolisys?
Thanks!

Try it and see
The starter has the biggest current draw so providing the easiest path for the current makes a lot of sense to me
I think iron conducts electricity better than aluminum

I think aluminum conducts electricity much better so I think you're fine.

https://www.metalsupermarkets.com/which-metals-conduct-electricity/

I see several errors on his information, gold is the best conductor, hence the gold plating of high end connectors for the high end devices, especially in the aircraft and space programs
Basic electricity classes cover the different metals used in the power and entertainment industry, the power company converter to aluminum lines to save money even though they have to have to use a bigger line size compared to copper lines.

We do it in the racecars. Both aluminum blocks but we have even seen excessive corrosion on the outside if they are not grounded.

I need to correct the above, Silver is best, but it tarnishes, where gold does not why gold is favored. For example, in FE racecars, the wiring is mainly pure silver.

What is FE race car?

Sorry Formula Electric

https://www.fiaformulae.com/

Grounding to the head is no problem, especially if you're also grounding to the starter or to the block next to the starter. What are you using for coolant? Distilled water might help if you are using tap water. Some sort of additive is also a good idea such as water wetter or something like that.

I moved my battery to the trunk on my Dart and only ran a hot wire to the front. To ground the battery I drilled and tapped a hole in one of the roll bar mounting plates welded to the trunk floor. The engine ground comes from a bolt in the k member to the aluminum head. There is another wire from the bolt on the k member to a ground buss for any accessories, I also have a sacrificial anode in my aluminum radiator.

No grounds on my heads. Ground cable in the back to the cage. 2nd ground from the torsion bar cross member to the transmission. 3rd ground cage to block. I did see corrosion between the water pump and motor plate, none between the plate and block. Also some pitting around the water jackets in the deck surface of the heads. I'm going to add an anode and see what happens. Never any electrical or misfire issues.
Doug

Is this the series that replaced Formula one?
If so I saw part of a race on T.V. of those cars and watching them accelerate away from a corner was not very exciding with out any exhaust note of the motor accelerating , no tire squealing noise or anything else

Welcome to the future.

The kids won't know any better.

I believe the hidden OP's original question, I can't see how any electrolysis he thinks he spotted has anything to do with grounding on the head, but that is only my guess.

There is an Anode in a radiator cap for this.

https://www.ebay.com/itm/Anti-Electrolysis-Sacrificial-Anode-13lbs-Radiator-Cap-FREE-1-3-DAY-SHIPPING/202005618264?hash=item2f08791e58:g:uhoAAOSwPt9eoHQe:sc:USPSPriority!83617!US!-1

On my Duster I used one cylinder head as the negative buss bar. I have the battery post connected to the head as well as the chassis, the EFI system, the electrical panel, and the ignition system. I ground everything to that head. The heads are drilled at tapped in multiple places so it is easy to attach a bunch of wires to it. The head is central in the engine compartment and it is aluminum so it conducts well so it seems like a natural place to run all of the grounds to.

Thanks for all of the replies, I think I will continue to ground to the head.

Good to go. But I'd still think of putting an anode in some where. They also make drain plug replacements that screw in the radiator.

Grounding both heads will help with electrolysis when it's running, you have a basic battery exchanging ions through the coolant due to the dissimilar metals in the heads and block. Adding an easier "path" for the electrons flow will help reduce the electrolysis effect on the head studs,head gasket fire rings etc and technically,you get a better spark. I run an earth from the batteries in the trunk to the block, the starter motor turns the engine over a lot easier. Sure it adds weight but your ignition system will thank you.
EDIT: Some coolants also have corrosion inhibitors which will help also but not all drag strips like you to run anti freeze / summer coolant

With all of those bolts or studs clamping the heads down, how could there be any difference as to which is grounded?? When using an ohm meter on block and heads, I get zero ohms. Type of gasket material would make zero difference. It even shows a 0 ohms reading from block to oil pan sealed with a thick paper gasket and silicone.
I've always ran a ground from frame to starter mount, and from frame to battery in trunk, Zero corrosion issues on the alum. heads.

i have read in a few places not to use distilled water. I'm not a chemist but it was said that distilled water has been stripped of all minerals and when you put it in you motor it will eat the metals to try and balance itself back out. it said use softened water whatever that is.

Softened water is water that has been run thru a water softener, removing most of the dissolved minerals. Distilled water is boiled water vapor, recondensed from steam into water, which has no minerals in it. I have been running distilled water and anti freeze in all my vehicles for years - no issues. There are no minerals to collect on the radiators internal tubes to clog them.

Softened water is any water that is un-distilled and then has salt (Sodium Chloride) and potassium added. Good for your laundry, not good for drinking.

Distilled water makes good coffee. But it should not be drank as a main water source due to the lack of minerals.

Tap water all depends on where its from and how its treated if at all. Well water may be full of good and bad.... Tap water from a Miniciple source can also be full of good and bad....

I have for the last 35+ years just added a 50/50 mix of distilled water and good ol GREEN stuff.

But with this 410 Stroker build I am installing an anode into the front and rear block drain plugs. There is enough room for a 0.90 inch long Zinc or Magnesium bar. I bought 5 of these for $20 and am just cutting them down to fit. The end I cut off can be threaded and used later so I really have 10 on hand. I will replace them every 2 years or so. See picture below

https://www.ebay.com/itm/Martyr-CME0-1-3-4-L-5-16-18-Thread-1-4-3-8-Dia-Plug-Engine-Pencil-Zinc-Anode/254316970289?hash=item3b36790131:g:~YAAAOSwZGFdQqeh

EDITED> The Ebay link for 5 pieces of these Anodes
https://www.ebay.com/itm/ZINC-ANODE-PENCIL-WITH-PLUG-70-E00C-SIZE-1-4-X2-PLUG-1-8-NPT-5-PACK-MARINE-BOAT/184015710240?hash=item2ad830e820:g:O6sAAOSwF1dUPrmk

I am not sure how much current is or how long any current is actually running thru an Alum Head. as AndyF mentioned its effectively a bus bar, and I can't believe any current induced into the head connection "likes" the coolant instead of the massive amount of Alum to flow thru. I believe electrolysis occurs and is a concern rather independent of any typical grounding scheme, and I have yet to read anything that makes for a case otherwise.

At FCA we have an EMC lab. They bombard new cars with radio waves and all types of electrical interference. All the new heads are aluminum, many aluminum blocks as well. But no corrosion issues. Working in the electrical lab I tell tell you that grounding is taken very seriously. I have yet to see grounded heads or a full ground cable from a rear mounted battery.????
Doug

OK, going from the factory location up front I will ground using a 2 gauge cable to the front of the left cylinder head. But I also run a 10 gauge to the core support. Then from the backside of the right head I run a 6 gauge strap to the firewall at the voltage regulator. I also like to run a ground strap from the alternator to the block.

When running a rear battery I ground using a 1 gauge wire from the battery to the starter's lug on the block. I also run a 10 gauge to the rear frame rail and a third long 10 gauge up front to the core support. Same 6 gauge from right head to firewall.

With 45 years as a Telephone repair tech, Bonding and Grounding is VERY important. All connections should be clean. Then the nuts torqued to 40 Inch Pounds.

I think a better test than Ohms would be testing for Voltage Drop at each point. I'll bet there is some but very minor.

Ohm drops (gains) would be in the 0.00010 Ohms and most digital 'Auto Ranging' VOM's will not see that.

using a electrical meter to measure conduction you need to use the MHO scales, not the OHMS scale
I have ben advise to use those measurements in very low voltage circuits, not that I did it though

I don't doubt that observation one bit. However the reasoning behind it, vs what we are discussing, is I believe the modern OEM's to save wire costs, complexity, and by more effective design and attention to detail, have been able to produce a chassis/unibody that forms a nearly universal ground plane for everything electrical on the car. Our decades old cars did not have that consideration, and also suffer from a decent amount of weather induced corrosion, etc. I see an added ground directly from battery to engine as a huge preventative measure of future electrical gremlins in our old cars as we add more electrical components..

Exactly.