getting ready to wire my car when wiring 6 volts do i have to wire it positve ground ? or can i go the same way you would wire 12 volt? with black to ground ie frame and body and red to starter then to voltage regulator? any good diagrams. its a model a roadster my battery will be in the trunk so ill have to run it up to the starter. before i get jumped on from people telling me to run 12 volt not doing it . i have had 6 volt cars before and never had problems just looking for some good wiring advice on 6 volts i will be running heavy gauge cloth wiring.thanks billy
Yep the 6 Volt Fords ran positive ground. If you are going to stay with 6 Volts I see no reason to switch to neg ground. You won't be running any modern neg ground accessories so why change? I don't get caught up in the color of the cable dictating the pos or neg side of the system. The mid 70's Ford pickup that belongs to my mom and is sitting out in my driveway is color coded backwards. not a good thing when someone goes to hook up jumper cables. I'd run a heavy duty ground strap from the battery to the frame and then one from the frame to the block up front. Then I would run a heavy duty battery cable from the battery to the solenoid but I think I would stay with black. From there the color coding is your choice. If you are wiring from scratch I would suggest wiring one system completely before going on to the next. Such as taking care of the start and ignition system and then doing the charging system. Then tackle the head and tail lights, turn signals/stop lights, horn and what ever else you are going to run. Make sure you draw out the system either before or when you do it and mark down the color code and wire size as a reference for later. That will save a lot of time a couple of years down the road if you have to troubleshoot the wiring on the side of the road.
Good luck running a 6V battery from the trunk. The voltage drop for that length of cable is going to be significant...even 00 welding cable might not be enough depending on the strength of your battery... Nothing wrong with a well-maintained 6V system (positive or negative ground), but I don't think I'd ever build a car from scratch using one. Even simple things like headlights are tough to find when you're on the road... The bigger reason is peace of mind - I can let my '40 sit all winter & it has more than enough juice on 12V to spin the thing over enough to prime the pump & fill the carb bowl before it finally fires (although I usually pour a bit down the carb to help speed things along). You'd never, ever do that with 6V. You get three, maybe four good (10+ seconds) cranks & they're done. I'd leave it positive ground myself simply because that's how it came, but I can't think of any polarity sensitive items (other than coil - maybe heater blower?).
Don't forget to run a good ground from the body to the frame. I have seen a mechanical temp gage cable turn red hot when the body ground was left off.
I agree with Flat Ernie about the battery in the rear. I've seen boxes made for them under the p***enger side of the seat where the curtains went so that they dont sit below the frame. Those six volters needed as short a run as possible to the starter.
Just a thought, if you are positive ground and need a jump start, you are pretty much up a creek. 12 volt to 6 volt same polarity jumps are possible if you are careful with the timing of it. Also, if you go negative ground, remember to polarize the charging system for the polarity change.
It actually does not matter for jump starting, always hook up positive battery post to positive battery post with your jumper cables , the battery is still a battery, if you start welding then you have them on backwards
Jump starting doesn't matter polarity wise - just don't let the steel bumpers touch - seriously. Keep the cars apart & there is no problem.
Stock "A"'s with the battery in the original position use a #1 size cable to the starter and you need an equivalent size on the ground side. Some early "A"'s had a solid ground strap. I'm using the stock battery location and grounded my battery to the trans when I start on the lights I will run a cable to the frame. I used a piece of 2/0 welding cable for the ground. Overkill but I had the cable. I have a 9n selinoid set up and I am cranking an engine with 8 to 1 comp. and a V8 Al flywheel so I need all the help i can get. I considered going with an 8 volt but didn't want to worry about blowing the lights. You can buy a regulator from a company that makes them for 6, 8 or 12 with your stock generator. The company is Fun products.
No reason to use negative ground unless plan on switching to 12V in the future, which you probably aren't going to
I'd try to copy the Ford pattern. Here are several early Ford diagrams. I'd go with a diagram from the 40s because I'd recommend using a generator and regulator from those years. I drove a 36 Ford p/u for a few years and the cut out would kill the battery at times. You eliminate that with a more modern generator and regulator. If you use the 32 column drop and switch, follow the ignition circuit from a 30s Ford schematic. A 6V starter solenoid is wired differently than the 12V units that most us are used to. You'll need a reproduction Ford starter ****on also to make it work. Just follow the Ford schematic. If you keep it simple and follow the ford schematic it will be easier to trouble shoot down the line. The lights are no problem. Follow a 40s schematic even if you use a modern universal switch. As the others have said, I strongly recommend putting the battery as close as physically possible to the starter motor. Either under the floor or under the seat. Nothing is worse than coming out of the 7-11 with a cold slurpee and the car won't start. I've been there. It's no fun. The guys speak the truth. It's a common problem with 12Vs in the trunk let alone 6V. I'd use star washers at EVERY battery cable connection.(pos. & neg.) Make sure all terminals and connections are clean and bright. Your choice of 6Vs makes it more critical. 12V systems can over come some extra resistance...6V systems can't. If it's a flatty I'll be jealous of the sounds of the starter motor when you spin it over. The flatty has a very distinctive sound when starting that you lose with 12 Vs. You can tell a 6V flatty from 1/2 a block away. I've had several 6V Fords. Make your own schematic before you start pulling wires. Lay out the components on the paper just like they will be in the car. It will become apparent how you need to run the wires. Think of each system as a separate system, starting, ignition, lights etc. etc. Some of the systems will run along with other systems. That will make bundling easier. One wire at a time and when there are no more wires to run...you're done.
Hot dang! I did not know that. I'll have to ponder the current flow as I drift off to sleep tonight to grasp how that works.
If the distance is a problem with voltage drop, you might think about running an 8vlt tractor battery to get an extra kick. It works OK with the 6 vlt starter,and lights and what not. Might adjust the regulator to charge a little extra for it. I learned the trick from a friend's dad, and he still runs one in his 50 Merc. with the original flathead. It gives a little extra fire. You can also run it with a Pertronix 6vlt Pos. ground module.
Optima 6v are strong enough to go from the trunk to the starter, they have something like 800 cranking amps compared to 450 for the stockish type. Use the thicker weld cable like stated above, it's equally as important. -on the old red dot roadster had a red top OPTIMA, had some cool thinner green battery cable- if the car didn't start by the second try, the cables would get hoOot! The starter didn't go as fast too. Swapped out for some fat weld cable and it was like a new car. I went with the negative ground and it works fine, some say that it pits the points of the regulator/distributor faster but not sure after 7 years... Also 6volt NEEDS GROUNDS EVERYWHERE! Engine-frame-battery-body-generator-lights... and it needs to be clean from oil and dirt over time! Good luck! TP
+1 on the Optima red top. It is so much smaller(6V) and can be mounted on its side opening more possibilities on mounting locations to shorten up the cable AND much more cranking amps.
ok i think i got this figured out i talked to jack tonite and he said he had a 12 volt system in 1947 so that about gives me my answer he ran his battery in the trunk i have a pic of it. now i just have to figure out if my gen is 6volt or 12? my motor came out of a running 39 ford that was updated in the 70s to a 59 ab and a 40 ford rear so i think it was 12 volts. i need to check. how do you check the gen to see if its 12 or 6v? thanks guys for all the input. billy
If you'd like for me to save you the pondering, I'll explain it. Each car has its own floating ground, meaning that they aren't tied together to a common ground (such as each other or Earth ground). In other words, if you were to take a voltmeter and touch one probe to Earth and the other to the frame, you'd read a voltage difference. Remember, your frame is not touching Earth Ground (the tires serve as insulators). If you touch the frames of a positive and a negative grounded cars together, you are in effect shorting both batteries out (the bumpers would serve as a conductor and since one cars positive lead is tied to ground and the others negative lead is tied to ground (which is now a common ground) and you have a lead going between both the positive and negative terminals... you'll have a little acidic bonfire beneath the hood. John
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