Grounding Question

Members,

The way the grounds were configured when my car was assembled doesn’t seem right. I only have the negative battery cable going to a bell housing bolt and no ground wires between battery and chassis or chassis and engine.

I think I should put a ground stud on the frame near the battery and run a ground strap from the engine to the stud and from the battery to the stud. Then battery, engine and chassis grounds will all be tied together.

Opinions?

The setup you describe will introduce another connection into the starter circuit that can corrode and cause problems over time.   Add the stud to the frame and run a separate cable from the engine to the frame stud while leaving the current ground cable where it is.  This accomplishes the same thing, but keeps the high amp starter circuit as simple as possible.  I like to put the main ground cable from the battery under one of the starter mounting bolts, but it will work where you have it now.  Connecting it to a starter bolt provides the best potential ground path for the starter since the cable is in direct contact with the starter itself.

Some starters can draw well over a hundred amps (maybe over 200 during cranking!) and need the best connections you can provide.  This is why poor battery connections can cause starter trouble well before you have any other indication.

Also, are you using the chassis as a ground for any of your other circuits?  If not, there is nothing wrong with adding a ground to the frame, but it won't be doing anything.

Lack of grounds is a common problem on not just fiberglass bodied cars, but also most every '60s and '70s cars. If you take time to read through the Ron Francis tips on the website, it explains a lot.
I have a bunch on mine and added a bunch to the '66 British car i'm building now.
Grounds are even more important on all late model electronic everything cars.
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Please excuse this post. It was a duplicate post so I deleted all the text

I’m hoping that adding the ground from engine to chassis will solve problems like the temp gauge not reading correctly. VDO said that the temp sensor needs a good ground path from body of the sensor back to the gauge.

Was the temp sender installed with teflon tape or some other type of pipe sealant?  If so, then it needs to be removed.  Sealant will cause a bad ground.  Also, corrosion can develop over time between the manifold or head and the sender.  This can affect the reading too.  You may need a pipe thread tap to chase the threads in the hole to get a good connection.

The cable connected to the engine from the battery should provide all the ground you need there, but as Jerry said, you need good grounds to every circuit in then car.  The under dash circuit may have insufficient grounding.  If the rest of the cars circuits are connected to the chassis, then the new cable from the engine to the chassis might help, but if they are connected somewhere else, it won't.