1952 Chevy 6 V to 12 V Conversion (1949-1954)

Wow! Very very well written. Thank you so much for taking the time to put this info together! Thanks again

 

A couple additional things:

If you decide to go to a later ignition swtich with the Accesory terminal, most any 1960s GM dash switch will install in the dash and the stock outer collar should go right on - there were that I know of no changes in the basic design of these in this period other than the various terminal changes for each car. You may even be able to use your existing lock cylinder in it.

The same goes for the heater fan. GM didn't change that design much, ever - I've used fans made a dozen years apart for entirely different cars in place of one another. If you can scare up a 12V fan it's just a matter of whether you want to change the cage on it, or the one it has is the right depth to work in the existing heater. Quite often the mounting flange is the same size and the bolt holes are almost all in the same places.

For that matter, it wouldn't be a big deal to put 12V car horns in, either.


If someone's scratching their head wondering why no mention was made of the starter, the 6V starter will work fine on 12V. To change to a factory 12V starter on a car with a 216 or 235 requires the flywheel also be changed as the tooth count is different on the gear and ring. That's a lot of work on a car that still has the torque tube in it.


A lowbuck source for a 3rd brake light would be the strip light found in the wings on some later model cars; cheap particularly if you can get one in a you-pick yard, just a single row of LEDs and would be very unobtrusive in the rear window.

 

This'll help me along a lot when I get to this point on my Pontiac, so thanks!

 

Seems to me there should be an idiot light or diode in the excitation circuit? Without it the alt. will back feed the coil and not allow the engine to be shut down with the ign. switch.

Figure 6: After, Modified Charging System with 12 V Alternator

 

The drawing does need either a lamp, resistor, or diode in the excitation line.

Also the sense wire should go directly to the battery post. This will allow the internal voltage regulator of the alternator to produce the correct charging voltage at the battery. The wiring from the alternator will have a voltage drop when charging at a high rate. Therefore the sense wire raises the alternator output voltage to make sure the charging voltage is high enough for battery to charge.

Reference the following from the threaders first post. It calls out the diode issue.



To wire the alternator you will need the DA plug from the Fifth Avenue Garage. His has, I believe, a diode in-line which allows you to shut off your car. I got mine from Speedway, Part No. 91064100. Without it, even when you shut of the key, power will be fed back through the excitation wire back through the ignition switch and to the ignition coil, keeping the coil energized, thus not allowing you to shut your car off.

 

The license plate lights use #63 on the 49, i replace them with #5007.
Pat

 

67 bulbs will work on license plate lights too.

 

Great post, it will be a huge help on my 53 210!

 

awesome post! cant wait to do this to my pile!

 

Does the lighting also apply to 49 chevy trucks? Needing bulbs and have a 3100 half ton

 

Probably. I got all the 6 V to 12 V conversion from a table in the Fith Avenue 12 V conversion guide.

 

If you do not have a DA plug with a diode, you can loop the sensing wire to the battery terminal on the alternator as shown and the other wire can go to the accessory side of the ignition switch. The alternator will not feed back into the ignition circuit if done this way and the engine will NOT keep running when the ignition key is turned to off.

 

Good point. A newer ignition switch will have an ignition and a separate accessory terminal. But, if you don't have an accessory terminal, you would need a diode. I have since sold this car and can't recall if it had separate ignition and accessory terminals on the back of the ignition switch.

Either using an diode or making sure you have a separate accessory terminal on your ignition switch will solve this issue.

I did find a P/N number in a Painless Performance chassis wiring harness instruction manual for a diode, Radio Shack Diode 276-1661. It would need to be installed with the stripe towards the alternator.

 

I'm needing to do this 12v on my 49. This looks to be word for word and something I can do. But I see some disagree. So is there something should be change or is this good cause I'm going to go out buy tomorrow and start the conversion

 

Thank you for taking the time to post this thread. My 50 was converted, but after seeing the way some things were done, I'm going to start from square one when rewiring it. Your post will be a great help. Thanks again.

 

This is the book i ordered it would work right
http://www.classicpartsusa.com/product/LIT-11_1949/1949_Truck_Parts_Literature

 

That's a great book that will help you through it and was my first read when I converted mine from 6V to 12V.

 

I think some questioned the sense wire, whether it should go to the batter or just to the back of the alt. I've seen it done both ways but back to the battery would be better to get a true battery voltage reading.

One guy questioned the diode or need for an idiot light. If you have an ignition switch with a separate accessory terminal then use that terminal to excite the alternator. If you don't know, add the DA plug from Fifth Avenue Garage or a Radio Shack Diode in-line and you won't have any issues.

Good luck. If you have any other questions I can try and help. Make sure you post up how it went for you.

 

Thanks and if I have any questions I'll get on here

 

So I need a Lil help or got a question. I'm in process of this post I'm converting. I just installed the alternator and the resistor for the gas gauge. But the da plug directions say hook straight to starter solenoid yellow wire excitation wire red wire to battery if I remeber correctly for the red wire that is or maybe it was to battery post on alternator can't member off hand

 

Sorry but I'm having a little trouble understanding what you're trying to explain. Here's how I wired my DA plug:

1. Yellow Wire -- The excitation wire was hooked to the ignition switch, 12V key on. (The excitation wire needs to be hooked to a switched 12V source with key in run.)
2. Red Wire -- The sense wire I hooded directly to the back of the alternator output terminal. (See Figure 7 of my post.) I was told it's better to run it to the battery, but I think where I wired it works just fine.

Good luck!

 

Great info.

 

I'm sorry your directions say go to ignition and the directions in with the da plug say go to state. Now they are all connected by your diagram. But if I go to starter as da plug directions say it just gets closer to battery as I'm seeing it. Now the generator wires and the voltage regulator wires I do not use at all right cause it's all internal.

 

My question are flashers voltage sensitive being just a quick recovery curcuit braker?

 

Nice post, thanks.
mine is converted, but using a 12v generator, I will be using this to change it to an alternator.

Jim

 

Lots of good info

 

Good info. Giving this thread a try on my customer's 1954 Belair. Has a hard time starting. Quite certain 12 volts will fix allot of issues.
350amp draw at 5.3 volts during cranking. Starter motor was checked out, by local rebuild shop a few years ago.
Car is so original and been in family almost since new. Hate to change it, but I think it's time. Plus guy is moving up to SC, so I'll not be able to work on it.
JT

 

Great thread

 

Thanks to everyone who has contributed, I have learned a great deal. I anticipate buying an Anglia (Popular) here in the UK in the relatively near future and 6 volt electrics are very much the weakest point of that range of cars. This will help me no end. All beautifully written as well.