How to use 12v negative gnd gauges in a 6-volt positive gnd car

[Eaglescout2457]

Good evening, I have a 1953 Mercury Monterey with an 8BA flathead that is 6-volt positive ground. I understand that the gauges that come factory are not completely reliable and am looking to add aftermarket gauges to my car. I have looked for older style gauges and have stumbled across the Stewart Warner Green Line series gauges. Unfortunately, these only come in 12v negative ground. I am looking to add 2 temp gauges (one for each head), A Tachometer, and am deciding whether I would like an Oil pressure Gauge or Amp Gauge. (I am running a Power Gen alternator with a max output of 60 amps). Is there a way to convert these gauges to work with my car? Photos to show how awesome the gauges look. any help would be awesome, Thank you!

[cas3]

Prolly not gonna happen, but there are smarter folks than me

[tubman]

Originally Posted by Eaglescout2457

Good evening, I have a 1953 Mercury Monterey with an 8BA flathead that is 6-volt positive ground... temp gauges (one for each head), A Tachometer, and am deciding whether I would like an Oil pressure Gauge or Amp Gauge. (I am running a Power Gen alternator with a max output of 60 amps). Is there a way to convert these gauges to work with my car? Photos to show how awesome the gauges look. any help would be awesome, Thank you!

I would rethink this if I were you.

BTW, I find that the Ford King-Seeley gauges to be accurate if used properly. I am not a fan of 12 volt conversions, but have seen that there are simple ways to retain them when converting to 12 volts. Ford themselves did it for a few years. As I remember, the mid fifties Merc dashboards have considerable appeal of their own.

[Eaglescout2457]

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I did not convert my car to 12v, I am keeping it 6v and I am keeping the original gauges except the amp gauge. I am running a power Gen alternator and was told by the manufacturer to not hook up the amp gauge because it could cause a fire if overloaded due to a higher current. I have a flathead that I have put a ton of time, money and patience into, and I want to make sure that I have no issues with temp on both sides of the engine. do you have any recommendations for a 6v solution? Thanks!

[TJ]

The original gauges work just fine. They do need proper grounding for the senders. If you really think you need new gauges put in some new mechanical gauges.

[tubman]

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What I did on my '51 is to move the sending unit from the passenger head to the driver's side head, and eliminate the crossover wire. I then installed an aftermarket mechanical temperature sender in the passenger head and ran the tube to a gauge mounted in a two gauge auxiliary panel on the bottom of the dash. I added a mechanical oil pressure gauge to that panel and ran the tube to a tee on the back of the block. I considered an oil temperature gauge in that spot, but I already had an spare oil pressure gauge (and I'm cheap).

Belt and suspenders. BTW, I found the stock Ford temperature gauge responds faster to the initial increase in temperature than the mechanical gauge.

Nice lookin' engine; what are you running for carburetion and a distributor?

[Eaglescout2457]

Ok, I think for now I will stick with what I have. Hopefully everything works. replaced the whole harness with an original style cloth covered in the car. I just got the last couple things I needed to complete the dash and engine wiring. I am hoping to start the car for the first time since buying it 2 and a half years ago this weekend!

[cas3]

good luck, 1st starts are always fun

[fortyonerag]

I love original dashboards, but I fitted mechanical gauges under the dash of to my 41 when it was 6v. Fit 6v bulbs and you are good to go.

I was satisfied to find I had much better oil pressure than the original gauge told me! It was also comforting to know the temp readings were accurate, and easily confirmed on the bench with boiling water before you install.

If you are fitting under dash aftermarket gauges, have a look at the small Smiths gauge that is half temp & half oil pressure. It's small and can be tucked out of the way, also both gauges are mechanical.