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| | | | Joined: Oct 2021 Posts: 6,791 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,791 | I know that it's possible to reverse the polarity simply by switching battery cables. None of the electrical stuff will care except the ammeter.
What needs to be done with the ammeter to allow it to function?
Also, when did GMC switch to (-) ground? Was it when the whole company went to 12v?
A friend of mine has a GMC coach and an Austin taxi that are both (+) ground.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Feb 2019 Posts: 4,479 AD Addict & Tinkerer | | AD Addict & Tinkerer Joined: Feb 2019 Posts: 4,479 | Just swap the wires on the ammeter. You will also need to reverse the polarity on the generator or it won’t charge. I did that over 50 years ago on a ‘58 Pontiac, so I don’t know that procedure. I’m sure Jerry will gladly give us the lowdown.
Phil Moderator, The Engine Shop, Interiors and Project Journals1952 Chevrolet 3100, Three on the Tree, 4:11 torque tube Updated to: ‘59 235 w/hydraulic lifters, 12v w/alternator, HEI, PCV and Power front Disc BrakesProject JournalsStovebolt Gallery Forum | | | | | Joined: Oct 2021 Posts: 6,791 'Bolter | | 'Bolter Joined: Oct 2021 Posts: 6,791 | Thanks.
I do know how to re-polarize the genny. Jump BAT and ARM on the voltage regulator.
1950 Chevrolet 3100 (Ol' Roy)
1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1964 Ford Galaxie 500 coupe |1966 Ford Mustang (Little Red) | 1969 Pontiac GTO (The Dishpit) I 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
| | | | | Joined: Jan 2022 Posts: 2,450 'Bolter | | 'Bolter Joined: Jan 2022 Posts: 2,450 | when did GMC switch to (-) ground? Was it when the whole company went to 12v? V8 equipped GMC (I don't know about the really big trucks) trucks switched to 12 volt positive ground with the second series 1955 models. Six cylinder equipped 10x through 41x models which didn't change until the 1956 models.
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12
'52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
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