If everybody stuck with the standard GM practice of the 1960's we'd be in trouble here. Stock cams, 700x14 tires, drum brakes, points/condensers, etc.
Explain to me how RFI suppression occurs without current flow? I started working on radar in 1965 so I'm familiar with RFI, but I've never seen it work unless you had current flow. Why are these non-current flowing 'ground' straps made of a fairly substantial braided cable? If you hook them up, how do you keep them from flowing current? If you hook them up and your electrical problems are diminished, do you remove them to revert to the 'standard' GM practice then spend a buttload of money trying to figure out where your grounding problem is? I don't think I would.
Yeah, it's a good thing GM doesn't practice your its own sage wisdom..... Unlike radar technology and tire technology GM grounding systems have NOT changed very much in the last 50 years. My 2000 Chevy I ordered new is set-up the same as a 1969 Chevy. 2 battery grounds. One directly to the engine block and one to the body. No engine to firewall straps.
Take a look at an assembly manual sometime. You know where you find the "firewall straps"? Try UPC 12, under RPO U63 and U69. Guess what? Subtitled "radio suppression".
Take a look at a virgin original "radio-delete" vehicle. Guess what? No factory straps.
Try to find a TSB (technical service bulletin) that specifically states for service techs to "inspect" the braided suppression straps when the customer complains of hard-starting or dash instrumentation issues. Good luck with that.
Ever see a new old stock radio kit that the dealer would have on a shelf to install a radio? Guess what's in there? The straps. Guess what? No mention that the straps are there to "help with grounding the electrical system of the vehicle". Because that is NOT what they are for.
Why so "thick". Does it really matter? Where are the typical mounting mounting points for these straps on the engine? Valve cover bolts you say? Let's see, last I checked the torque for those bolts is not 40 lb-ft! Something that is just "snug" isn't going to safely carry large current amounts. They are thick because they had to be braided flat to give them enough composition to hold up with the heat, vibration and jerking of the engine under load. That is why there is no insulation on them as well, that would have quickly melted and deformed being "draped" where they are.
I'm not going to respond any more to this thread. It's simply foolishness when people suggest to start adding grounds from engine to frame and firewall when they have issues with their electrical systems. Add all you want, but people just don't understand the GM design. Only 2 main grounds are needed. One to the block and one to body to handle the current demands of the vehicle.
The only reason there are problems with something built in 1965 or 2005, is there is a lack of understanding (I see it all the time on many GM message boards) of how the system is MEANT to work, so the components aren't properly maintained and then they fail OR are not restored properly during reassembly.