6v-12volts?

[rossbart]

One more quick question:

I am not familiar with a positive ground system - this is my first. I appear to have everything running 12 volt (except coil which is resisted down to 6 volts. I want to add some 12 volt electric guages in this interim time so I can monitor water temp, oil pressure, etc.. On a positive ground system do I need to wire everything in reverse of what I'm used to with automotive and 12 volt negative ground? In other words, on the guages, do I need to ground the positive wire to chassis and the black wire to the battery negative circuit with an inline fuse on the battery negative circuit?

I would assume so but am certain that there is a vast storehouse of knowledge here that I'd like the benefit. Thanks for any help to the new carrier owner.

ROss

[Jim Price]

Ross,
I used and recommend the booklet, "The Official 12-Volt Conversion Guide" by Randy Rundle. I picked it up on eBay. It was a lot of help!

Regards,
Jim

[Grant Bowker]

http://www.fifthaveinternetgarage.com/
Available here any time for $US10.00 plus the usual shipping etc., no need to wait for an auction. I haven't dealt with them but they've been advertising in Hemmings for quite a few years.
They also sell alternator pulleys to fit a variety of belt sizes and brackets to mount alternators to either Chev of Ford engines of the vintage used on CMPs.

[Lynn Eades]

Many older vehicles can be converted from +ve earth to -ve earth by changing the battery around, and re polarising the field magnets in the generator ( as simple as wiping a wire,hooked to the new live terminal of the battery, to the little terminal of the generator)Any alternator is not able to be changed easily. Instruments are not usually polarity sensitive, but some are.Generally speaking, fuel, temp, ampmeter,and oil pressue gauges are not polarity sensitive. Its generally the charging system that needs the attention. repolarising the 'fields" as I have just mentioned is all that is needed, but it must be done immediatley after the battery is reversed, and before the engine is run up. Otherwise the regulator and generator will burn out. Usual warnings, Check with an auto electrician.

[rossbart]

Thanks Lynn for the info. It's just the guages that I'm concerned with right now. So, I think I'll just try them as normal (but with an inline fuse just for insurance) and see if they work. Guess that will tell the tale won't it...

Ross

[Jim Price]

Ross,
It's your system but before you go ahead please consider the following: To be able to use your original dash gauges with a new 12 volt system you will need to install a voltage reducer such as a Runtz tranistorized voltage reducer on each electrical dash gauge except the Amp gauge. A Voltage gauge simply needs to be "tweaked" to work in a 12 volt system. Using these will provide you with accurate gauge readings as well as prevent them from being damaged from excessive amperage or inaccurate voltage.

Regards,
Jim