Technical Running A SBC on 6 Volts in a 6 Volt Car

It really is... Some of the solutions offered are way too complicated IMO (two batteries! Relays and big cables between them! Charging issues! Where are you going to hide all this? Sheesh!) and doesn't need to be. If the existing harness and switches are in good condition, they are more than adequate for 12V operation. Here's a list of things to be addressed.
1. Lighting. Simple, swap all the lamps to 12V and you're done. Don't forget the clock, radio and courtesy lights...
2. Gauges. Another easy fix. Ford used 6V gauges from the late '50s into the late '70s, look at the back of any Ford instrument cluster from that era and you'll find a voltage reducer just for that. There is a caveat however... When Ford changed to printed circuit boards on their clusters in the late '60s, the reducer 'snapped' onto the board like a 9V battery, so no screw terminals or mounting bracket. Look for the earlier version. And IIRC, the tachometer on those is mechanical, that can of worms you'll have to open for yourself...
3. Ignition. Again, easy fix. If you intend to run points, install a ballast resistor in the coil power feed wire. For easier starting with the resistor, swap your '55 starter solenoid for a newer one with the small 'I' terminal next to the 'S' terminal. Connect the 'I' terminal to the coil side of the ballast resistor and you're done.
4. Heater fan. If the motor is in good condition, it will run on 12V. It'll spin faster is all. But if it fails, 12V direct replacement motors for the '56-57 'Bird will bolt in. About $70 if you shop a bit.
5. 6V Starter motor if you end up with one you want to use. Same deal as the heater fan, except don't grind on it for extended periods. Keep 'on' time to under a minute, with a 5 minute cooling off period between. Lots of guys doing this...
6. Clock. If by some miracle you have a 70-year-old clock that still works, one of the gauge voltage reducers will work. If it needs repair, it'll probably be easier (and just as cheap) to have a modern 12V movement installed.

This leaves the radio, power seat and windows to deal with. You have multiple choices here for how to make these work.

You could use dropping resistors, but each one would have to be sized for its load. And you'll need one for each load, for a total of five (radio, two motors for the seat, and one each for the windows). These can throw off a lot of heat if used continuously, so the one for the radio would need to be mounted somewhere where it can dissipate the heat safely. The seat/windows are intermittent use, that shouldn't be an issue. A fair amount of wiring would be needed, probably along with a couple of relays.

Another choice takes us back to the two six volt batteries in series. No big relays or cables needed, just tap the power for these off the center. Two things I don't like about this; one, using the radio will introduce that 'charging imbalance' which may be an issue. The seat/windows shouldn't be an issue for that. The second thing is the availability of six volt battery sizes/quality levels isn't what it used to be and isn't getting better. A failed battery could leave you stranded. Again, some rewiring needed and probably a couple of small relays.

Last, just bite the bullet and convert these to 12V. The seat and windows are easy. The only difference between the '55 and '56-57 parts is the motor voltage. New 12V motors for both the seat and windows are available, they are a bolt-in deal, no rewiring needed. Pricey though... the window motors are about $270 each, seat motors $300 each although I didn't search particularly hard for a better price. If your window regulators are iffy, NuRelic sells a new complete bolt-in set for both doors, regulators and 12V motors for $500, but you'll have to add some relays if reusing the existing switches. And this is a good place to note that each 12V option will require replacing two existing 6V relays (the 'couple of 'relays' mentioned above). When accessories like AC, power windows or seats was ordered, the wiring for these wasn't incorporated into the main harness. These used an 'overlay' harness added to the car and was fed power ahead of the ignition switch, usually protected by a circuit breaker. To allow key control, a relay was used in each overlay to kill power when the car was shut off (although the seat may not be switched. Some aren't). The 6V relay won't last long at 12V. A 30A Bosch relay will fix this.

Last of all, the radio. If you're lucky enough to have one that works, count your blessings. Now, I'll throw this out here; many years ago (50 at least) a guy who supposedly knew what he was talking about told me that to 'convert' a 6V radio to 12V, all you needed to do was change out the 6V vibrator for a 12V one. I never did this or saw it done, so verifying with a tube radio guy is definitely called for. If it doesn't work, the usual fix is to semi-gut it and install solid-state guts. There are guys who can restore these to OEM, but it will likely be just as expensive as the upgrade and tube quality these days is crap in spite of how much they now cost. There are guys that do the upgrades, but you can also buy a DIY kit.

All this help?

 

Steve, how are you crazy?

Everything you said is entirely rational. I got to thinking about it earlier today, and I realized I really like the Bluetooth option on new radios. Just learned how to use it in the last two weeks.

They make a retro radio for my Bird that has Bluetooth. It only works on 12v... Might be a sign.

 

Steve is correct... Just bite the bullet and do it properly.
My conversion on my Lotus was a dedicated competition car . And I really needed 24V on a 12v starter to crank it over fast.

If you want Bluetooth, don't even bother with a radio conversion [just disconnect it] and simply use a bluetooth amplifier under your seat, and use your phone as a receiver / remote control.
Doing it that way is non-invasive , and can be removed / restored later. Unless you are and Audiophile a $30 bluetooth mini amp is pretty damn good. [you just need good speakers]
I have a bluetooth amp in my 57Chevy and my house has them hidden in several rooms [powered by 12v AC Adaptors from a computer]

This thing is the size of a Cigarette packet and pumps out 100w. [There is no volume knob, you use your phone]
It has a built in "phone jack" so you and plug in a 3.5mm audio cable and it automatically switches over to Aux input [unplug it and it defaults back to bluetooth]


Electronics have come a long way since the 80's

 

X2 on just using the factory radio as a dummy dash filler .... though definitely make sure the lights work on it. On my 53 bel air I did that and mounted a modern stereo hidden under the seat.

 

Kerrynzl, who manufactures the one you have in your hand? I can't make it out.

I really enjoy the way you think my friend. It's way outside the box. I like it.

 

Does a '55 Bird have electric or vacuum wipers? Can a 6V wiper motor survive prolonged 12V use?

 

Ford stuck with vacuum wipers until the early '60s...

 

I know I’m late to the party, but my 55 bird seats have been running on 12 volts since 1999. Windows since I put them in since 2011. I used a 12 v unit when I went to electric wipers. Clock never worked anyway, and radio was 12 volts so just threw the 6v-12v converter away. Easy.

 

Not a fan of voltage resistors to run a 6 volt radio on 12 volt as I have seen radios expire doing that. They really need the tubes, vibrator and power supply updated to 12 volt to work properly. I prefer a regulated power supply to provide 6 volt rather than resistors other than the small ones designed for gauges.

 

I figured that the 6V seat/window motors could tolerate the 12V for the short periods they are on, my concern was that the mechanisms they drive may not be able to take the additional power produced on 12V. You've answered that question.

 

Mimi [my wife] did a complete thread here on the install [you'll recognize the first photo]
https://www.jalopyjournal.com/forum...th-sound-system-install-non-invasive.1155455/

The first post has a "fleabay" link where to buy them. [grab a couple at the same time to save shipping costs]

 

I'm very skeptical of the output ratings on these type devices. With a supply current of only 5 amps @ 12V that is only 60 watts of input power. They are claiming to be creating an additional 140 watts of power out of thin air, an impossibility.

As a comparison, my home audio amplifier produces 500 watts per channel, but requires 1800 watts of input power to do so. And before you ask, yes, I am an audiophile...

 

They have discovered the "holy grail" of physics which is "over unity"

An Audiophile usually has "the set up from hell" in their home, not in an old car which is an Acoustic nightmare.
I am far from being an audiophile after beating my eardrums to death with 50+ years of hanging around racetracks and engineering shops.
I need some background music to help me deal with Tinnitus

I just tested the one of these Amps fitted into my living room 2 days ago.
I made some inline barrel plug connectors so I could hook up a multimeter to it.
Normal "easy listening" is about 0.8a to 1.2a draw

Then I cranked up the volume and it was drawing 6.5a [81.25w at 12.5v]
This is input but doesn't necessarily equate to output.

Ironically I also downloaded some "Vivaldi" classic music onto my phone and tried it! It peaked slightly higher at 7.2a ["rock and roll" and "metal" couldn't go that high]

My amps are powered by a 12.5v x 8a AC adaptor with 12v wiring in the ceiling!
I wanted to see if the AC adaptor could handle the Amp plus 2 x CCTV cameras [between 0.18a and 0.35a] together.
This would save me a lot of wiring and fishing wires down walls for the cameras.

 

KERRY, my tinnitus almost goes away with hearing aids.

Ben

 

By the time you swap in the SBC, figure out how to do whatever it is you're gonna have to do to make it work, couldn't you go through the 331 and just put it in the car? Why do all the work and expense to swap the Chevy when you could rebuild the Hemi and just do it once? Seems like it'd end up being less time and money in the long (and short) run.

 

I don't disagree with you. I've had the 331 since 2016. The biggest problem I've had with it along the way is that vendors who have made parts for these have dried up and what's left is very questionable.

The SBC is still the heavy weight champion of engine swaps. Because of that, parts are cheap and available. If replacement parts are garbage from one source, there is another source to buy better parts. It's great.