1934 ford ground question

[mikebell]

Have 1934 ford pick up with 6 volt positive system. As a temporary fix I am mounting a 12 volt negative battery in the bed (stand alone).to operate a 12 volt gauge. Can I still use the frame to ground since the frame is already 6 volt positive ground, or play it safe and wire directly to the negative post. For now can't see spending 500 dollars to convert to 12 volt if entertaining a 302 conversion or keeping the flathead!

[rockfla]

I would play it safe and wire the ground back to the source

[JSeery]

Not sure it's clear what the 12v battery is doing, just connected to the starter or the whole system?

[V8COOPMAN]

Says he's using it to power a 12v NEG ground gauge.

If it's only a closed-loop circuit from BATT POS to gauge, gauge grounded to frame, and frame grounded back to BATT NEG, using ONLY the frame as a "common ground" with the 6v POS GND system will work perfectly fine. DD

[JSeery]

Sorry, I guess I have no idea what a 12v Neg ground gauge is. Maybe my brain is just not working today, but no idea what that would accomplish.

[Tinker]

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Makes me wonder what gauge is so important to have to go through all this trouble. Most important gauges have a mechanical equivalents. water temp and oil.

Didn't realize you could use a common ground -DD, thought that would be problematic.

[V8COOPMAN]

Originally Posted by JSeery

Sorry, I guess I have no idea what a 12v Neg ground gauge is. Maybe my brain is just not working today, but no idea what that would accomplish.

Just an example.........you need coffee! Yes, there are probably simpler ways to accomplish whatever it is that he's trying to accomplish. DD

[V8COOPMAN]

Originally Posted by Tinker

Didn't realize you could use a common ground -DD, thought that would be problematic.

Sounds spooky, huh? As long as the 6v POS GND and the 12v NEG GND circuits EACH remain as a closed loop unto themselves, the frame (for instance) can be used as a COMMON ground.

How many among us has questioned about safely using a 12v battery to jump-start our 6v POS ground cars? The logical answer has always been to first make sure that ALL 6v accessories are turned-off (such as a 6v POS gnd. radio), so that 12v and "unfriendly" grounding CANNOT be realized by the radio, EVEN THOUGH the radio remains grounded to the chassis. Second step is to turn-on the normal 6v POS grounded ignition switch (to power the coil). Third step........connect 12v POS jumper cable to big starter lug. Then, connect 12v NEG jumper cable to starter case, or engine block, or chassis ground. The starter will crank until you remove either of the jumper cables. Most-importantly, you have just mixed 6v POSitively-grounded....with 12v NEGatively-grounded (using the SAME, common ground), and all is still well. DD

[JSeery]

So were talking about running everything on 6v except the gauges? Talk about making life complicated.

[Tinker]

Originally Posted by V8COOPMAN

Sounds spooky, huh? As long as the 6v POS GND and the 12v NEG GND circuits EACH remain as a closed loop unto themselves, the frame (for instance) can be used as a COMMON ground.

How many among us has questioned about safely using a 12v battery to jump-start our 6v POS ground cars? The logical answer has always been to first make sure that ALL 6v accessories are turned-off (such as a 6v POS gnd. radio), so that 12v and "unfriendly" grounding CANNOT be realized by the radio, EVEN THOUGH the radio remains grounded to the chassis. Second step is to turn-on the normal 6v POS grounded ignition switch (to power the coil). Third step........connect 12v POS jumper cable to big starter lug. Then, connect 12v NEG jumper cable to starter case, or engine block, or chassis ground. The starter will crank until you remove either of the jumper cables. Most-importantly, you have just mixed 6v POSitively-grounded....with 12v NEGatively-grounded (using the SAME, common ground), and all is still well. DD

Makes sense.

[V8COOPMAN]

Originally Posted by mikebell

Can I still use the frame to ground since the frame is already 6 volt positive ground, or play it safe and wire directly to the negative post.

The best example for relating how a COMMON ground is perfectly-safe between 6v POS gnd and 12v NEG grd........think about a 1955 Chevy (12v, NEG gnd) giving a push to a 1949 Ford (6v, POS gnd) on a cold, dark night. The Chevy creeps-up behind the Ford with it's run-down battery until the bumpers make positive contact (BOTH cars are now electrically grounded TOGETHER via their frame-mounted bumpers). Both have headlights on (it's dark), and the Chevy has it's heater blowing on "HIGH" (it's cold). With a short push, the Ford is running again, yet nary a mis-grounded, or mis-directed spark was found to create any objectionable, electrical smoke. DD

[mikebell]

From thread starter. Most fuel Gauges are now 12 volt negative. Rather than convert my whole car over to 12 volt -- may decide to keep old flathead-.Im trying this. Makes for interesting conversation !
.

[JSeery]

Originally Posted by mikebell

From thread starter. Most fuel Gauges are now 12 volt negative. Rather than convert my whole car over to 12 volt -- may decide to keep old flathead-.Im trying this. Makes for interesting conversation !
.

Not sure the 12v conversion is that difficult, might be worth a consideration.