After pulling my power brake vacuum booster for painting, I decided to clean up the top portion of the firewall and paint it as well. Question: Do the horn relay and voltage regulator mounts need to have bare metal contact when they are installed to the firewall? There is what I believe to be an engine ground strap that goes under one of the voltage regulator attaching screws. I know proper grounding is important and want to put everything back right. Also, how many grounding straps are there, and where are should they be located? '72 Cutlass, but with a '73 engine. Thanks, Chumley

 

Wow.
I'm suprised you didn't get a response to this. Yes they need to be grounded.
You can paint the firewall. The relay will ground through the screw.
A little tip, put a shakeproof washer between the relay and the firewall. It will ensure a good ground, and help secure the relay from being loosened when you're under the hood doing other things.

Jim.