1938 Oliver change to 8 volt

[Andrus]

Among a few other tractors, I have a 1938 Oliver 70. It's all rebuilt and looks great, but the 6 volt battery has a hard time turning it over. Usually I pull it to start it. I've heard I can have the generator re-wound to change to an eight volt system. what other things will have to change? Cutout? It runs on a mag, and has all new wiring.

 

[CobyRupert]

Pardon my ignorance, but why not change it to 12 volt?

 

[lman]

We had a 66 and it seemed like we used the crank or parked it on a hill most of the time.

 

[Gee Ray]

to the best of my knowledge there’s no such thing as an 8 V battery. As others have suggested the best you could do is just convert it to 12 volt.

 

[Andrus]

Pardon my ignorance, but why not change it to 12 volt?

That's not ignorant,...but can a generator be rewound to 12 volts? It's a very tight fit in there because the Oliver has side curtains. I see there are 12 volt generators available but I'm not sure they'd fit.

 

[Andrus]

to the best of my knowledge there’s no such thing as an 8 V battery. As others have suggested the best you could do is just convert it to 12 volt.

Oh yes, there are 8 volt batteries, I think they're often used for marine engines.

 

[rScotty]

to the best of my knowledge there’s no such thing as an 8 V battery. As others have suggested the best you could do is just convert it to 12 volt.

Eight volt batteries used to be common. It was a common fix because the old 6 volt starters were so weak. This was before anything automotive or tractor had 12 volts.

A starter will run on any DC voltage. The problem is that as you raise the voltage from 6 to 8 or 12 volts, the starter resistance doesn't change so that means it will also draw more current (amps).... That makes more powerful and turn faster... but it is a problem because the starter also gets a lot hotter. In fact, often hot enough in a few seconds to melt the old insulation - maybe even the internal starter windings.

Eight volts was a compromise... a little more powerful starter and not enough heat to cook it.

My own preference nowdays is to replace with a 12 volt starter and battery. You have a mag, so the ignition isn't changed. All you need to do is change the generator, light bulbs, and the voltage regulator - then you should be good. A generator & VR out of a late 50s to 60s Ford or Chevy might work fine if yours is fanbelt driven. Everything else besides the starter are not going to be affected by a little more heat.

On the starter itself; you may find a 12 volt starter to fit. I wouldn't be surprised if a vintage parts place online has them. Or you can always have yours rewound, but that might be harder to find anyone today to do. Any 12 volt battery will work. Get an AGM type. Group 24 is plenty.

rScotty

 

[Gee Ray]

I learn something new everyday.

 

[Smokeydog]

Did similar conversion on 1958 Ford 860. Original 6v. Switched to 8v battery for years. Then to 12v by using a used one wire alternator. Had to saw the of the aluminum mounting points a little and make a new tension arm to fit. Kept OEM starter. New bulbs and coil. Always started reliably for another 20 years.

 

[fidowanttobe]

I was going to do this 6-8 conversion once but instead upgraded to a 1 wire 12v alt because the battery salesman advised that the 8 volt battery would have a short life because it would never be fully charged to 8 volt by the 6 volt generator.