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If you are trying to decide if 12 volts is the way to go for an antique car or truck the answer is nearly always, YES. A car or truck has many more accessory circuits, turns much higher RPM, and goes many more miles than any farm tractor. Getting modern 12 volt accessories to work on a 6 volt system is often more trouble than it is worth. In most cases, the only good reason NOT to go with a 12 volt system on a vintage car or truck is if you are doing a complete original RESTORATION.
However, if you are working on an old farm tractor, there are some good reasons to leave it as a 6 volt system. My current preference is to leave them as 6 volt positive ground systems unless the generator and starter both need to be rebuilt soon. So, before you start stripping the nearly indestructable vintage generator and 6 volt wiring off your antique tractor, let's make sure you are doing this for the right reasons.
This is hopefully an unbiased view of both sides of the 6 Volt vs 12 Volt conversion issue as it applies to Antique Tractors. There are some very strong opinions on both sides and both sides have very good points to make. Here are a few pros-and-cons:
1—There is nothing inherently wrong with a 6 volt system. Millions of very reliable vehicles were produced for many many years before 12 volt systems became the standard. None of those vehicles were defective or unreliable. The modern standard for automobiles is changing again. The new standard may be 24, 36, or as much as 48 volts! Do you think your current 12 volt vehicle will suddenly become less reliable?
2—Converting to 12 volts will not fix a bad starter, solenoid, switches, ignition, or wiring. In fact, doubling the voltage will often cause some less-than-perfect parts to fail.
3—Most of the problems people are having with 6 volt systems are caused by poor maintenance. Converting to 12 volts will not fix a tractor that has not been properly maintained. If it was unreliable at 6 volts, it will not suddenly become reliable at 12 volts. The additional maintenance necessary to keep a 6 volt electrical system working properly costs nothing more than a little time to take apart and shine connections. Those same faulty connections will cause a 12 volt system to fail, it just takes a little longer and burns up more stuff due to the higher voltage. The 18 amps available from your generator might let the magic smoke out of a few parts. Run 100 amps or more from an alternator through the same failed component, and the fireworks can be really impressive! Instead of a little smoke we now have flames!
4—The original 6 volt system on your tractor has been working just fine for 50+ years. With a little maintenance, and occasional repairs, the system could certainly continue to function properly for another 50+ years.
5—The 12 volt conversion (done right) will always cost more than simply fixing the existing 6 volt system. Even if you can steal some of the 12 volt parts from a donor vehicle. "Done Right" is the key. There is no such thing as a "standard" 12 volt conversion. There are some conversions that work well, and are reliable. But there are literally hundreds (maybe even thousands) of attempted conversions that don't work at all.
6—In this case "done right" also means replacing the starter with a 12 volt starter. The 6 volt starter will work but if this was an OEM system, they would not use a 6 volt starter and expect the system to be reliable. Too many conversions quickly destroy the old starters, and drives.
7—Durability–Very few alternators being used on conversions are as robust and bullet-proof as that simple old 6 Volt generator. Look at it, you are trading a sealed generator unit with a solid steel case for an alternator with an open, ventilated aluminum case. Most alternators appear to be designed for applications with some protection from weather. Water running off the hood got into the guts of my alternator on the 48. The alternator guts were completely rusty and died in 9-months!
8—Breakerless? To the purist, this modern technology has no place on an antique vehicle. But, let's face it, the reason we see so few 8N tractors at shows, is that most of them are still "working tractors". They have a job to do and anything that could potentially increase reliability is at least worth a look. Simple economics says I can replace points 5 to 10 times for what one breakerless setup costs. A set of points should last at least a year and most go a lot longer than that. Anything over 5-year payback is hard to sell but some people claim much better reliability with the breakerless setup. My 6 Volt 1952 8N tractor was tuned-up and got a new set of points in June 2006. That tractor has been very reliable, usually starts on the first try, and didn't need a new set of points until October 2013! I do run a point file (burnisher) through the points and check/set the gap about twice a year.
1—The entire motor vehicle industry moved to standard 12 volt electrical systems about 50 years ago for very good reasons. If everything else is equal, OEM 12 volt systems are more reliable and require less frequent maintenance than OEM 6 volt systems.
2—Most modern accessories are intended for use on 12 volt systems. If you plan to have more than the ignition and a few lights on your tractor, the original 6 volt system will quickly be overwhelmed. The generator on these old tractors only puts out about 18 Amps max. The most I have seen on my amp gauge is about 12 amps. Maybe my generator is a bit tired? Compare that to at least 60 amps from just about any alternator.
3—If you frequently operate your tractor at night, headlights and taillights take a lot of power. A 12 volt system can easily run much higher wattage (brighter) bulbs. More power can be delivered over the same wire size.
4—Jump-Starting is less-confusing (safer) when the voltage and ground on both vehicles match.
5—Your 6 volt starter will crank the engine much faster at 12 volts. This makes it easier to start a nearly worn-out engine with low-compression. This may allow you to put-off doing an engine rebuild. Again, in my opinion using a 6 volt starter in a 12 volt system is not reliable. A 12 volt starter will still turn the engine over faster, and should be considered in the cost when doing the conversion or soon after.
6—If you are "points challenged" there are breakerless electronic conversions available for both 6 and 12 Volt tractors. These modules replace the points and condenser inside the distributor with a more modern breakerless system.
7—Good quality 6 volt batteries are getting harder to find. Fewer choices equals less competition and higher prices.
8—If you have a 12 volt donor vehicle available, you might be able to do your conversion for low cost. Some tractors built in the 70s had OEM 12 volt generator systems. The 6 volt generator can also be rewound as a 12 volt unit. This might save the trouble and expense of adapting mounts to install an alternator. Another plus is the wiring for a 12 volt generator system is exactly the same as a 6 volt system and the generator systems can be switched from positive or negative ground by just turning the battery around and polarizing the generator.
That should cover the major pros and cons. These lists could be a lot longer, but the point is there are many good reasons to go with 6 or 12 volts. Doing a 12 volt conversion certainly shouldn't be the no-brainer I originally thought it was when my first 8N tractor needed to be fixed up.
You have been warned. Maintenance is good for your soul. One of the reasons I like vintage gas-engine tractors is I can do things like fiddle with the points and turn screws on the carb. Very few things in life are as satisfying as chugging down your driveway on a machine you fixed yourself. If you happen to have an aptitude for things mechanical, reading instructions is optional. There is magic in knowing what goes on inside a piece of machinery from hands-on experience. When you know how something works, and what it takes to repair it, you are less likely to abuse it. When you become more familiar with a machine, you begin to better understand it's limitations, and automatically become a safer operator.
Modern automobiles have become more reliable and require less-frequent maintenance, but at what cost? We have traded inexpensive maintenance procedures for less frequent but MUCH more expensive repairs. Your 8N tractor will very likely still be chugging away and making people smile for another 50 plus years. That new shiny SUV you just bought will have been crushed, recycled, and forgotten.
Honestly, it is totally up to you to evaluate your tractor and your needs. Either way you decide to go will not hurt my feelings a bit. At the end of the day, IT's YOUR TRACTOR.
When someone contacts me to help fix wiring problems, we usually spend more than a few minutes just figuring out what they have. With either 6 or 12 Volt systems it is often easier to pull all the wires off and start over. Thankfully, there are only about nine or ten wires on one of these tractors, so even a complete rewire is only about a $25 job.
With either 6 or 12 Volts, when you have problems with your electrical system, it is always MUCH easier to get help if your wiring is as close to original as possible.
Clean every terminal and connection before you do anything! Take apart and use a small file to shine faces of nuts and terminals where current is supposed to flow. Replace nuts and washers at the first sign of corrosion with new zinc-plated hardware. Do not use stainless steel or copper hardware, it will cause any steel it touches to corrode much faster!
Replace your ignition switch.
Make sure your battery cables are the correct size for 6 volts. Skinny 12 volt automotive type cables are useless.
If the starter seems slow (or won't crank at all) make sure the mating surface between the starter housing and the cast iron block is clean and shiny. Do not depend on just the mounting bolts to provide a good current path.
Make sure you are using solid copper wire core spark plug wires, not the automotive resistor core wires.
Replace your ignition switch.
Running ground wires from head lights and tail lights to the same ground stud where the battery is grounded will make a huge improvement in the brightness.
All switches should be checked with a decent ohm meter to make sure they are in good condition. They have typically spent years out in all sorts of weather and frequently are the source of many electrical problems. If you find any resistance across a switch, replace it.
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If you are looking for more information on wiring and wiring harnesses, you might find what you want on my general wiring page HERE., kl. If you have decided 12 volts is right for your tractor click HERE to go to the 12 volt conversion page.
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