If you strip the car and paint all the interior metal pieces where the lower dash bolts to the hinge pillar and area on the firewall above the steering column where the dash mounts, and also paint the lower dash at the outer edges where it mounts, the chances of the dash being grounded are slim. All of those areas on my 69 when I stripped it down were bare metal.

 

If you strip the car and paint all the interior metal pieces where the lower dash bolts to the hinge pillar and area on the firewall above the steering column where the dash mounts, and also paint the lower dash at the outer edges where it mounts, the chances of the dash being grounded are slim.

My guess is this is exactly what happened in my case. I don't currently have the block in the car and temporarily have the negative cable on the radiator support. Depending where I probe on the dash frame. the best I can get my ohm meter to show is ~87 ohms to the neg terminal--even though I show a good ground on a bolt through the firewall. As suggested by another response in this thread, I think I will run a separate ground wire to ensure a good ground on the dash frame.

 

I'm doing a ground up build of a '69 Mustang......"

".........Should the dash frame be grounded and if so, how is it usually grounded?

I'm not as familiar with the '69's wiring, but on the '65/'66's there is a ground wire from the instrument panel to the dash metal framework. Several ground wires associated with the instruments and gauges use the same grounding location.

So yes, it is important, and makes me think the later years must have an equivalent arrangement. It won't hurt as thing to make up a couple of grounding wires and place them from the panel to any convenient nearby location on the metal framework .

Z

 

When I installed the ground wires (I connected a wire from each head) between the heads and the firewall I attached them to the firewall with 5/16" bolts instead of sheet metal screws. I used 1" long bolts which left a section of threaded shank exposed inside the car. I then attached ground wires between these bolts and various parts of the dash. Since my negative battery cable is attached to the engine block and the heads are securely bolted to the block I think that I have a fairly good ground circuit for electrical devices.

 

I'd say I have 3 options:

1) Leave it, assuming 85-95 ohms is just fine.
2) Pull the kick panels out and get the hinge pillar connection points and the dash support brackets into clean metal.
3) Run a good ground strap from the frame to the dash.

Right now I was leaning to #3. I'm not sure if #1 is sufficient since I don't want to have grounding problems down the road. Any thoughts on the options above?

 

#3 will take about 5 minutes, and you will be trouble free. A 14 gauge wire will be more than big enough.

Z

 

Over on the 69stang forum there are a few guys who are almost finished with their ground up restorations. One guy ran a ground wire directly from a battery up front to the dash area. He then made a connection spot for all his aftermarket stuff to ensure good grounding.