Re: Changing Positive to Negative Ground on 56 GMC

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Posted by Bob on October 20, 2006 at 04:41:06 from (69.178.229.154):

In Reply to: Changing Positive to Negative Ground on 56 GMC 450 posted by Sandy on October 16, 2006 at 18:58:22:

"B- Remove the residual charge in the Generator by touching a jumper wire from the Positive Battery terminal to the Field contact on the Voltage Regulator."

NO! NO! NO!.... To polarize the generator(it's an "A" circuit system), you momentarily jumper the "BATT" and "A" terminals at the voltage regulator. NEVER put battery power to the "FIELD" terminal! You will let the smoke out of the charging system!

Polarize AFTER re-connecting the battery with(-) ground polarity, and BEFORE restarting the engine.

And, you are not "removing the residual charge" from the generator. You are switching the polarity of the residual MAGNETISM in the soft iron polepieces of the generator.

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"We 'think' that we'll need to go through the dash and switch guage wires, swap sender wires, etc."

NO!. The gauges used in your truck are NOT polarity-sensitive, and will work equally well with either ground polarity, with NO changes or mods, or swapping of sender wires. Even the 6-Volt (+) ground trucks can be switched to 12-Volt (-) ground with the simple addition of an electronic 6-Volt voltage regulator in the power source line to the gauge panel. (BTDT, got the "T" shirt.)

If the truck has an AMMETER, as opposed to an "idiot light", ALL wires get swapped between the posts, or it will read backwards.

Keep the wires that were on each post together, and swap each group from one post to the other. (There may or may not be more than one wire on each post.)

(This works with the GM gauges of that era, however SOME guage setups of other brands ARE polarity-sensitive.)

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And, don't let the "naysayers" tell you you will have weaker spark. As long as the primary wires at the coil get swapped so the (-) wire goes to the distributor, the spark polarity and intensity will remain the same as before.

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Please postback as to how this worked out for you!

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