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By Florida_Phil - 8 Years Ago
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I have been troubleshooting a dead battery problem in a 1955 Thunderbird I just bought. My 6 volt charger reads fully charged, so I noticed someone put a Duralast 56 DL battery in the car. According to the Internet, a 56 DL is a 12 volt battery. The car still has the positive ground. Everything seems to be working including the radio, fuel gauge, clock, signal flasher, horns and lights. Is it possible the former owner converted the car to 12 volts with a positive ground?
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By oldcarmark - 8 Years Ago
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If you have a Voltmeter You can verify if it is in fact a 12 volt Battery. I guess it would work 12 Volt + Ground but the way to go is 12 Volt - Ground. There should be resistor somewhere to cut Voltage to 6 for Gauges and Radio if it is 12 Volts. Are the Bulbs in Lights 12 Volt? Is the Coil a 6 Volt or 12 volt? You are right about the 56 DL being 12 Volts. I have never heard of anyone converting to 12 Volts and leaving it + Ground. Interesting. On the Coil where the Small Wires attach there is a + on one Terminal and a - on the other. If its 12 Volt + Ground the terminal to the Distributor will be a +. If its - Ground and someone has the Battery hooked up backwards right now that Terminal to Distributor will be - on the Coil.
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By Florida_Phil - 8 Years Ago
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The coil is smaller in size than a regular sixties style yellow top coil. It has two posts. One post reads DIST and the other reads BAT. The DIST side is connected with a wire to the side of the stock 1955 Load-A-Matic style distributor and the BAT side is connected to a ballast resistor. The positive cable from the battery is connected to ground. The negative side is connected to a 6 volt single small post solenoid. Everything looks exactly as it should in a 6 volt car except the battery is a 12 volt battery. I am currently charging the battery with a 12 volt charger.
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By oldcarmark - 8 Years Ago
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That's an interesting One You have Phil. If its a 12 Volt System there should be a 12 Volt Style Solenoid with 2 small Terminals and a Resistor to drop the Voltage to Points. When You get it started after charging take a Voltmeter and connect to Battery. See what the charging Rate is from Generator. 12 Volt should be somewhere around 12.9-13.1. 6 Volt 6.9 approx. Interested to know what the story is with your Bird.
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By Florida_Phil - 8 Years Ago
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The battery is now charged to about 70%. The car starts and runs fine. A volt meter across the battery terminals now reads about 11 volts. As a test, I started the car with the meter attached and the voltage increases slightly as I rev the motor. This tells me the generator is working. There are no markings on the generator or voltage regulator, so I can't tell if they are 6 or 12 volt units. From what I have read, this is not suppose to work. At a minimum I would have burnt out the radio, clock and gauges. They all work perfectly. I don't see any additional resistors, but I haven't looked under the dash yet. I chould switch the polarity, replace the starter solenoid and coil, reroute the wire to the distributor to change the car over to 12 volts entirely. I'm worried that changing the polarity will hurt the radio and clock. but they are running on 12 volts now. Is there any disadvantage to keeping the car 12 volt positive ground?
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By oldcarmark - 8 Years Ago
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With the Car running it should show about 12.5- 14 across the Battery Terminals when You increase idle Speed. At Idle it would show about 12 as there is not much coming out of Generator until U raise Engine Speed. I would agree with You that its a 12 Volt System but it should not work without resistors for Clock Gauges and Radio. The ignition should have a 2 Terminal Solenoid with a bypass Wire from the "I" terminal to the "Bat" Terminal on Coil to get a full 12 Volts to start Car. I would assume there is a full 12 Volts all the Time to Coil which will shorten Point Life because no Resistor to drop Voltage to less than 10 once the Car Starts. I am not sure what would need to be changed to make it 12 Volt Neg. Ground like almost every 12 Volt Vehicle. Maybe Someone else could answer that Question.
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By Florida_Phil - 8 Years Ago
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The starter solenoid is definitely a six volt style with one post (no ignition post). This car is running a 12 volt battery with all the six volt hardware and positive ground polarity and everything works. I think someone swapped out the battery to a 12 volt unit some time in it's life with no ill effects, The battery is not new. I'm not sure why this works, but it exists. I think I'll do a little more research before taking any action. I have a feeling these old cars are a lot more flexible than we think.
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By Florida_Phil - 8 Years Ago
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I disconnected the clock and the old radio. I'm going to change the whole car over to 12 volts and be done with it. Thanks for the input.
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By oldcarmark - 8 Years Ago
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Sounds like U already have 12 Volts. I would check the Gauges for a Voltage Drop Device. They will not work very long on 12 Volts so I suspect there is a Resistor somewhere. Maybe on the back of the Dash Panel. The only Year that Ford used 12 Volts to power the Gauges was 1956. After that there was a little Device on the back of the Instrument Panel to drop the Voltage to the Gauges.
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By Florida_Phil - 8 Years Ago
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I have determined this '55 T-Bird has been converted to 12 volts positive ground. I pulled out the radio and it is a 12 volt positive ground conversion. I disconnected the clock as I read reversing the polarity will harm it. I suspect the generator, coil and voltage regulator are also 12 volts. The car runs great and everything works fine. The starter solenoid is the 6 volt style with only one small post. I disconnected the battery cable while the car is running and the engine stays running, so I assume the generator is working. It looks like all I need to do is to switch the polarity from positive ground to negative ground and I should be good to go to the next step. I know I need to re-polarize the generator when I do this. I have never done this before, but it doesn't look hard. Any pointers?
After that's done, I am going to replace the 55 distributor with a rebuilt 57 distributor with points and change the intake to a 57 with a Holley carb. I will also replace the starter solenoid and reroute the "I" wire to the ballast resistor. I have a set of '57 "G" heads to go on the car later. My goal is to end up with a 12 volt negative ground car with a 1957 Ford ignition and top end. Does all this sound like I'm on the right track?
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By oldcarmark - 8 Years Ago
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o Florida_Phil (8/6/2017)
I have determined this '55 T-Bird has been converted to 12 volts positive ground. I pulled out the radio and it is a 12 volt positive ground conversion. I disconnected the clock as I read reversing the polarity will harm it. I suspect the generator, coil and voltage regulator are also 12 volts. The car runs great and everything works fine. The starter solenoid is the 6 volt style with only one small post. I disconnected the battery cable while the car is running and the engine stays running, so I assume the generator is working. It looks like all I need to do is to switch the polarity from positive ground to negative ground and I should be good to go to the next step. I know I need to re-polarize the generator when I do this. I have never done this before, but it doesn't look hard. Any pointers? After that's done, I am going to replace the 55 distributor with a rebuilt 57 distributor with points and change the intake to a 57 with a Holley carb. I will also replace the starter solenoid and reroute the "I" wire to the ballast resistor. I have a set of '57 "G" heads to go on the car later. My goal is to end up with a 12 volt negative ground car with a 1957 Ford ignition and top end. Does all this sound like I'm on the right track?
That's very strange to convert it from 6 to 12 Volt + Ground. Wonder if this Car was in Europe at some Point in its Life? Many British Cars imported after WW11 through to early 70's were 12 Volt + Ground.
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By oldcarmark - 8 Years Ago
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The Generator will work on 12 Volt + or - Ground. To repolarize Generator turn the Battery around and hook it up as - Ground. Take a Battery booster Cable or a Jumper Wire and connect to the "A" Terminal on Generator and touch the other end to the + on the Battery. Just touch it for a couple of Seconds. To polarize the regulator take the Wire Terminal off the "B" Terminal and touch it to the "F" Terminal. Couple of Seconds. Will Spark. Normal. This is done with Engine OFF. The Radio should work on - Ground as its not like the newer Electronic Units. It should not work on 12 Volts without a Step Down Resistor which must be present somewhere under the Dash because it works on 12 Volts now. On my 53 Ford which I converted from 6 + to 12 Volt - I just added a step down Resistor back to 6 Volts and it worked fine. With it already being 12 Volts a lot of the changes have already been done like Bulbs and Turn Signal Flasher Unit.
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By miker - 8 Years Ago
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I think your on the right track, with the proper conversion and the dizzy manifold work with the heads. I thought I'd seen just about every odd ball thing on parts swapped out on old cars, but this one 12v+grd just shows I haven't. I would be interesting to know why.
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By Lord Gaga - 8 Years Ago
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IF; " The car runs great and everything works fine." why don't you leave it alone??
You'll have a car that fooled the experts! LOL
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By Florida_Phil - 8 Years Ago
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I thought about leaving it alone, but I don't want to be running around with some weird setup. Might get me in trouble some day. I'm not sure why this was done, but it is interesting to see it works so well. I'm going to switch the battery cables and re-polarize. Do both the generator and the regulator need to be re-polarized? I thought this was done at the regulator? Thanks for all your help. It's been a long time since I worked on one of these cars. The good news is it looks like the engine has been overhauled. The rocker shafts are new and the inside of the engine is clean. It runs fine for a '55 with a teapot carb, just not up to it's potential.
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By oldcarmark - 8 Years Ago
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I would do both just to be sure. Because the Generator has been running as a + Ground and the Regulator has to be done anyway.
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By Florida_Phil - 8 Years Ago
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I spoke to an old guy (actually my age) who has probably forgotten more than I will ever know. He owns a garage in the area and works on a lot of old Fords. He told me to switch the battery cables, install a new voltage regulator, flash the voltage regulator and I should be good to go. He said the generator is usually the first thing everyone swaps when to they go to 12 volts and the fact that my car is running well, it probably is a 12 volt unit already. I think he's right as this car runs too good to be messed up. I'm not sure why he wants me to buy a new voltage regulator, but they're cheap enough. Hopefully I can get this issue behind me and move on to more interesting things.
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By oldcarmark - 8 Years Ago
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No doubt the Generator is 12 Volts. Buy a new Regulator and Polarize it. Its not a big procedure to polarize the Generator just to make sure but that's up to You.
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By Y block Billy - 8 Years Ago
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To tell the difference between a 6 volt and 12 volt generator, the 6 volt rear bracket fits inside of the mount and the 12 volt fits to the outside of the mount if I remember correctly.
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By Florida_Phil - 8 Years Ago
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Mine is outside the mount, so I guess it's a 12 volt like we suspected. I'm wondering why the former owner didn't convert the ground while he was going to the trouble? It doesn't matter now. I've reversed the cables and installed a '56 and up style starter solenoid with the extra post. My car already has a ballast resistor so all I need to do is rewire the coil with the new "I" wire. The new voltage regulator is on the way. Hopeful, all will go well. Thanks again!
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By oldcarmark - 8 Years Ago
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. Florida_Phil (8/8/2017)
Mine is outside the mount, so I guess it's a 12 volt like we suspected. I'm wondering why the former owner didn't convert the ground while he was going to the trouble? It doesn't matter now. I've reversed the cables and installed a '56 and up style starter solenoid with the extra post. My car already has a ballast resistor so all I need to do is rewire the coil with the new "I" wire. The new voltage regulator is on the way. Hopeful, all will go well. Thanks again!
That's also interesting that You mention it already has a Ballast Resistor. Normally if You try to start the Car without a Bypass the Ballast gets fried right away. That's why the Bypass from Solenoid was added when 12 Volt System started in 56.
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By Florida_Phil - 8 Years Ago
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Whoever did this conversion did everything as required but left the electrical ground positive with the old starter solenoid. I have no idea why. The radio has a sticker on it that says it's 12 volt positive ground. It's DC, can't you just switch the wires on the radio from positive to negative? After I get the car running with a negative ground, I'll give it a try. This issue has been fun and I've learned more about old Ford electrical systems than I wanted to know.
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By oldcarmark - 8 Years Ago
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Florida_Phil (8/9/2017)
Whoever did this conversion did everything as required but left the electrical ground positive with the old starter solenoid. I have no idea why. The radio has a sticker on it that says it's 12 volt positive ground. It's DC, can't you just switch the wires on the radio from positive to negative? After I get the car running with a negative ground, I'll give it a try. This issue has been fun and I've learned more about old Ford electrical systems than I wanted to know.
That's really strange Phil. Before You switch the Radio I would ask someone who works on these Vintage Radios. There's several listed on the Internet. The fact that its tagged as + ground makes Me think this was not backyard Conversion by someone who didn't know what they were doing. I really wonder if this Car was not exported outside the USA at some Point. Very interesting Car U have.
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By Sandbird - 8 Years Ago
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Someone has probably added solid state circuitry to your radio for them to place that label on it. Solid state devices (eg. transistors) can be destroyed by connecting to the wrong polarity. The radio chassis is grounded internally to the radio circuitry, so you can't reverse two wires in this instance.
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By Florida_Phil - 8 Years Ago
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It is a solid state radio conversion. It's disconnected for now. I connected the battery cables with a negative ground, switched out the starter solenoid, ran a new wire to from the "I" terminal and reflashed the existing voltage regulator. The car fired right up with no issues. Generator is charging. Problem solved. Now on to the distributor and carb change. We are making progress. Thanks again!
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By Florida_Phil - 8 Years Ago
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The 57 Distributor went in like butter and the motor fired right up. The 292 sounds better already. Don't you love it when that happens!
What a piece of junk that tea pot carb is. I don't know why they even call it a 4 barrel? The thing was leaking gas all over the manifold. It's in the box now with the Load-A-Matic distributor. Putting on the '57 intake with new Holley 465 this weekend.
After I run it around for a few weeks, I'll swap the heads over to the 57 "G" heads with the high ratio rockers and exhaust manifolds. Funny, the 57 exhaust manifolds don't look much different from the outside. Should be running like a real Ford soon.
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By Dobie - 8 Years Ago
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"The thing was leaking gas all over the manifold."
Besides "teapot" they were also known as "the towering inferno"..
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