Now that my car starts and runs, I can start chasing down a few other oddities, namely what I'm thinking is a bad ground somewhere.

My headlights work sometimes, and at others, they don't. At some point in the future, I'll be replacing fuses and renovating electrical connections throughout the car with gentle abrasives, dialectric grease, etc.

So where are the ground points, aside from the negative lead on the battery?

One of the first items...I would spin the fuses in place in each of their locations in the fuse box. This could help to quickly create a clean connection. Also, with these bullet type fuses, I've run into some in the past that "look" ok, but where the ends have actually cracked away from the fusible trace.

Were you able to find the service manual pdfs online? Those help, too.

Hi Grubeguy

Re the fuses. if they look shorter than the others in the holders then the ends have melted too.

Normally the rocker light switch is the culprit on mine, with your work back round you should be able to take the switch apart and clean it inside.

i find the brake light switch normally needs a good bit of work after the cars not been used.

tim

Forgot to say

earthing points for the engine are either

between the tinplate under the clutch and screwed to the bulkhead just under the radiator.

And/or

braided cable between the water pump end and the rear panel mounting bolts

various others under the dash and behind the front lights

Tim

Re:- the battery negative/earth lead

Some Fiats, on the body side of this earth lead rely on a terminal (metal plate swaged around the lead) spot-welded to the body. This can cause problems.
If you have a multimeter/ohmmeter, check it out or alternatively drill a hole through this flag terminal, clean down to bright metal on both sides and bolt together. Apply petroleum jelly or other suitable treatment to inhibit corrosion.

Remember that many motor factors/auto-electrical suppliers stock replacement battery (and other) earth leads/braids in a variety of lengths, often at lower cost than buying the materials to fabricate your own.

A quick check if you suspect a problem with battery or engine earths is to use a battery jumper cable/lead to provide an additional earth and see if things improve e.g. a sluggish starter now works normally. On the 850, 2 battery jumper cables can possibly be joined together to reach directly from the battery at the front of the car down to the engine at the rear.

With lighting problems a temporary separate earth cable can be applied directly to the bulb holder to check if the existing earth is faulty.

Hth,

Al.

So right now, I've got intermittent isues with the tac (spinning the fuse solved that), intermittent gas level gauge, intermittent coolant temp gauge, and lights that don't like to work regularly.

Aside from the work I've done to the car, it's literally sat since 1976, when the original owner blew a head gasket and parked it. Coolant got into the engine and rusted it solid (thus the need for a rebuild). I have a lot of things to look at/renovate before I'm comfortable taking it for a jaunt around the neighborhood...