positive ground on 49's ???

[tonkadawg]

I finally got some time to look closely at the wiring on my 49 and noticed that the positive terminal of the battery is grounded to a frame rail. The negative terminal wires directly to the starter - truck is still 6v. All the wiring diagrams I've seen for this year say the truck should be a negative ground.

Anyone have any ideas of what's going on?

Can I safely swap the wires on the terminals and not do any damage to the truck?

Thanks,

Matt

[john]

Is it a GMC? I think they were pos ground until the mid fifties.

[solidaxel]

Originally Posted by tonkadawg

I finally got some time to look closely at the wiring on my 49 and noticed that the positive terminal of the battery is grounded to a frame rail. The negative terminal wires directly to the starter - truck is still 6v. All the wiring diagrams I've seen for this year say the truck should be a negative ground.

Anyone have any ideas of what's going on?

Can I safely swap the wires on the terminals and not do any damage to the truck?

Thanks,

Matt

I would think a DC motor hooked up backwards would run backwards!

[tonkadawg]

Originally Posted by john

Is it a GMC? I think they were pos ground until the mid fifties.

it's a chevy - at least the body and the title say it is.

Originally Posted by solidaxel

I would think a DC motor hooked up backwards would run backwards!

I would too!

I'm thinking somewhere along this truck's history, someone decided to get creative with the wiring. I'm thinking this might be the opportunity to scrap the wiring for a new harness and step up to a 12v system. This isn't that hard is it?

[mr48chev]

I'm with Tonkadawg: I would think that at the time the battery was put in the person who installed it was thinking that was the way to do it properly.

6 Volt Fords, I think 6 v Internationals and most British rigs had pos ground. Even my 55 Metropolitan was pos ground from the factory although I converted it to neg ground when I installed a chev generator in place of the Lucas.
Most of the time you only have to swap leads on the ammeter, and coil to make things work. I think the generator would have to be polarized too but I haven't had my hands on a working generator for close to 25 years.

But it could have just been stuck in the truck in error at one time or another time.

One way to check the intended polarity on a rig is to look at the leads on the coil. The side of the coil connected to the distributor will tell you what the intended ground on the rig was.

[BigJackDaddy]

Originally Posted by tonkadawg

I'm thinking somewhere along this truck's history, someone decided to get creative with the wiring. I'm thinking this might be the opportunity to scrap the wiring for a new harness and step up to a 12v system. This isn't that hard is it?

It's not hard and it's not necessary. If you just want a new wiring harness that's one thing, but you don't need to pull the whole harness when switching from 6V to 12V. As a matter of fact, the 6V harness will carry twice the amperage than 12V.

I know that Chevy used 6V +grnd on passenger vehicles in '54, so I wouldn't be surprised if your truck was too.

If you're considering converting from 6V+ to 12V-, wire it like 12 volt. The starter will get its ground through the case. Put the positive wire through the solenoid and onto the starter wire lug. Ground the (-) battery terminal to the engine block. The solenoid should eventually be changed to 12V as it will heat up, albeit only during extended cranking, no-start conditions.

You'll have to change the bulbs, and either change or add resistors for the heater motor, gauges, etc as well, but definitely not the harness. You'd be going to lesser capacity. 6V horns are much louder on 12V

SolidAxle,
Generally, a DC motor hooked up backwards will run backwards... perfectly, but because of the way they're designed, starters are a different breed - they're immune to polarity. Whether (+) or (-) grnd, it'll spin the same way and for reasons mentioned above, a six volt starter would be the equivalent of a very "heavy duty" starter if left in the system when converting to 12V.