Thinking Positive

R

rogtwo@aol.com

Guest
I'm planing to switch my Amphi back to positive ground. Before you try to
talk me out of it, please read my reasons below -- then try as hard as you
like. But, before I make the switch, I wanted to verify the following 2
things:

1) Will the starter-motor will still turn the correct direction without any
modification?

2) Will the heater fan still spin the correct direction?

I know my bulge pump will need to be rewired. But that's not a problem
because I just wired in a relay for the pump, and I can just swap the wires.

OK, so why do I want to go back to positive ground? Mainly because I like
the "originality" of it. Also, my gas gage will work without rewiring it,
and my battery cables will be long enough without getting a new battery with
reversed terminals. Besides, I have an old inverter that I can use to power
the radio and cigarette lighter (so it can be used as a power outlet for GPS,
cell phones, etc.).

Roger St. John
White '63
Seattle


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R

rogtwo@aol.com

Guest
Re: Re: Thinking Positive

Thanks Cap'n John

I will be using the Dynamo (Generator) that is currently installed. I hear
all I have to do is repolarize it the other way.

As for the coil and wiper motor, since I got the car recently and it was
already negative ground, I don't know it they were reversed or still wired
the original way. Hopefully the coil is marked + and -. Do you know which
terminal on the wiper motor is supposed to be positive?

Regarding isolation -- the nice thing about using an inverter is that it is
NOT necessary to isolate the radio or lighter from ground. Both can still
have their cases connected to the body of the car. This is possible because
the inverter gives you an independent source of 12V power. With two
independent sources of 12V, it is OK to have the positive side of one source
connected to the negative side of the other (much like batteries in series in
a flashlight). Below I have attempted to show a crude wiring diagram
demonstrating this (hopefully it comes out legible, but it may not due to
different font sizes)

- 12V + - 12V + <br>
| | ground | | <br>
| |_______| | <br>
| | | <br>
| | | <br>
|__Light__ |__radio___|


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A

a_colo_native

Guest
> 1) Will the starter-motor will still turn the correct direction
without any modification?

Yes

> 2) Will the heater fan still spin the correct direction?

Yes as will the bilge blower (if so equipped)

<SNIP> I have an old inverter that I can use to power
> the radio and cigarette lighter (so it can be used as a power
outlet for GPS, cell phones, etc.).

I will assume you are going with the original Dynamo and not a pos.
gnd alternator.
*Change your coil too, they tend to fry prematurely if reversed.
*Be sure your radio doesn't use the case or the speakers as a ground,
if so isolate it and your speakers from the body.
*If you choose to use the inverter on the lighter, Isolate it
completely from the dash or it will short out to the dash.
*You may need to add resistor spark plugs and a filter to minimize
the whine in your radio
*If you have the Petronic electronic ignition, you will need to
replace it too.
*If you reversed the wiper motor wiring, be sure to change it too
*Clearly mark your battery box as "POSITIVE GROUND" so nobody makes a
mistake if you need a jump.

Cap'n John
 
A

a_colo_native

Guest
> As for the coil and wiper motor, since I got the car recently and
it was already negative ground, I don't know it they were reversed or
still wired the original way. Hopefully the coil is marked + and -.

When reversing coils, they tend to weaken and fail soon after. It is
cheap insurance to just replace it before she leaves you stranded
somepace where AAA may fear to tread. Mark it as (-) GND and set it
aside as an emergency spare. Yes, they should have a (+) and/or a (-)
mark on them next to the terminals.

> Do you know which terminal on the wiper motor is supposed to be
positive?

Chances are that it will be fine. When going to (-) gnd they tend to
park about 3" above the bottom of the windshield but otherwise work
fine. If your's does that then it will probably park correctly now.
The change (if done) is internal and not at the connections.

Sounds like you have it whipped now! If I didn't drive my car
regularly, I would have kept it 100% original too. I do have all the
correct parts to go back to stock. I kept my regulator in the car and
wired "through" it. It is not functional, but looks like it is so all
that you see is the alternator. (kinda a big clue!)

John
 
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