Hot Rods HELP!! Want to start my Flatty on 12v but run everything else on 6v????

Hey guys i have a dilemma. I have an early Flathead V8 and i planned on running it 6v so i wired it with a 39-40 Ford eng harness with a Gen cut out. So the issue is with finding a fan set up that will work on my car(28 Phaeton) i tried a 1946 gen and drop down fan setup but the fan hits the rad. So i found an even earlier gen with the fan mounted in the snout of the gen but Now the fan hits the upper rad hoses and the gen is bottomed out on the intake.....So i have a 12v electric fan i can put on that will fit but will look like shit! Plus the eng turns over SUPER slow on 6v so i figured i would run a 12v battery and put a reducer on the wires going to the eng harness, lights etc and just run the fan and the starter on 12v....if that makes sense but how many amps is the system gonna have? I found a Voltage reducer that bring the 12 down to 6 but will only take 20amps MAX is that enough to run the rest of my car???? Info on the car, All it has is lights, ignition and horn! No radio, heater, signals or anything. Oh and will the 6v gen and cut out be able to maintain the 12v battery properly?

 

About all I can add is you can start a 6V starter wth 12V. Just don't keep cranking. Also my 1939 Ford has some sort of old style round reducer to the gauges and the SBC is a 12V. Everything except dash gauges is 12V on mine.
I'm hoping you can somehow adapt a mechanical fan to work. That engine and body does not need an electric fan sticking out like a sore thumb. Your girlfriend won't approve.

 

Yeah i have the stock A gauges so there not an issue its everything else

 

The only thing that will charge a 12V battery is a 12V charging system. Just convert to 12V and be done with it. The 6V harness is plenty big to run 12V components.

 

You can add a 12 volt battery for starting only. This guy tells you how:
http://www.bloomingdalecom.net/~billben/12vboost.htm

 

Ooops! I forgot to mention the 6V gen won't charge a 12V battery. I agree do it right or park it. Somewhere there should be a fan that will work. Flat heads have started on 6V since 1932 in the winter with snow on the ground, on a hill.

 

There is a battery that will provide 12 volts for starting and 6 volts for the rest of the car. !2 volts won't hurt the starter. Do not remember source. A good web search should turn it up.

 

Super slow cranking indicates a problem. 6V starters in good condition, with appropriately sized battery and cables, work just great on the engines they were designed for--by which I mean low-compression flathead motors. If you like the idea of 6V, stick with it, and chase out your problems.

 

I understand, i should try a bigger battery cable and maybe even a bigger battery. But what about my fan issue?? i am running out of options

 

What they said re voltage. For the fan, I run with the generator offset to the passenger side and mounted a fan using a 8ba fan mount held on the center/intake manifold mount. Let me know if you want a picture. One belt runs it all and seems to keep it charged and cooled. Hope this helps.

 

Yeah sure AV, if you could post a pic up that would be great!

 

Here you go. It took. Little machining as well.

 

hmmm that looks good! what did you have to machine?

 

Machined out a space for a bearing that I pressed into the pulley mounting the fan. The bearing was 3/4 Id. Can't remember the od but I think it was 1 1/2".

 

If you have room, you can run 2 6 volt batteries and a series/parallel switch so it will start with the batteries in series (12v.) and run and charge them in parallel (6v.)

 

I know this response will get a lot of "flak" but I have had approximately 8-9 flathead powered vehicles(over 50 years of hot rods) and NONE of these vehicles had a fan of any kind(electric or Henry Ford supplied).One of my cars was a 32 five window,full hood and fenders with a bored,stroked,big inch flatmotor with a S.CoT. Blower in south Texas that ran on the street over 10 years.I maintain if you have a "clean" flathead(water jacket wise) and a good radiator with good airflow and keep moving more than being stopped(yes overheating can occur if you hit 10/12/15 red lights in a row) but I don't let that happen.I don't run thermostats,but build 2 washers(1 for each head) with. 5/8-3/4 hole in the center to force the water to stay in the radiator longer to do what I think contributes to its main reason for better,more efficient cooling.I'm sure there are naysayers who will disagree with me,but it has worked very well for me personally.

 

Guess it all depends on just how much you want to tinker with the car.
Our three flathead cars are all 12 volt. Two I converted to 12 volt (a 36 & 49) after we picked them up and one I built that way (a 32).
On the 32 project, converted our generator to 12 volt and still had charging problems. Picked up a Powergen alternator (looks like a generator) - all charging problems solved. Left the regulator and all in place.
Works for us...

 

Really? that's pretty cool! maybe ill try no Fan as i wont be driving it in the city really. I always thought that Flattys were notorious for getting hot

 

I have 6v in my car and had problems starting. Turned out to be incorrect valve adjustment. Starts just fine now in cold and hot weather.

I'm done talking now

 

Pretty sneaky there ! Looks sharp.

 

Suggest you fix the starter first, or the wiring, or whatever is wrong. You will have to eventually. If you do it first it will save you the bother of changing to 12v. Millions of Fords started on 6 volts and so will yours.

You could cut the fan down so it clears, if you can't move the rad hoses. Just make sure you get all the blades exactly the same length and balance it.

 

I don't get it! Here's the starting scoop:

• 6 V starter in good condition
• big battery cables, copper of course
• real good grounds clean and several of them
• Optima 6 V (800 cranking amps)

My 38 is setup this way and will crank for 30 minutes if necessary. It is an 8.50 to one motor with a big Melling camshaft. Just sayin...

 

How slow is slow? 6 volt starters crank at about half the speed of a 12 volt under the best of conditions, if it's even slower than that, then you have other issues to fix which need fixin' anyway.
Adding a large resistor to drop the whole system from 12 to 6 is going to cause a lot of heat and wasted energy. Basically you'd be using soaking up half the electric power just to drop the voltage (the resistor will be "cooking" half your power, leaving the other half available for 6v accessories).
Or, you could just convert everything to 12V and keep the 6V starter, just beware that they tend to break bendix springs on 12V.

I hate electric fans, so I'd say Avater has a viable solution with the offset generator and 8BA fan setup.

 

this is what you need but they are not cheap ( $2-500 ) you can get a new starter or rebuild the old one or heavier cable for the price , we use these on many Diesels, Kenworths came with them stock , but they were 12/24V set ups but would spin a motor over like it was 2:1 compression and when cold (-10f) like it was 90* outside , I had a chevy tow truck ( 427T) with one on it and it about flipped the motor out of the truck when keyed but it would fire right up first keying ( unless it was out of gas) even in sub zero weather .and one thing your starter has to be up to it otherwise it can throw the windings out of it if its in bad shape or old .

 

Don't go with the 12/6 combo. Just one more thing to go wrong. Be sure your ground cables are thick enough and clean the connections. If it still cranks slow take the starter to a rebuilder. If you still feel you need something go to all 12 volt. If you are running a stock type manifold go to one from about '37 to '39 as they have a lower mount for the generator (PM me if you need one, or a picture to show what I am talking about).

Charlie Stephens

 

If I remember correctly, my T's Merc flatty ran an 8BA fan mounted upside down off the intake stud meant for the generator. Never ran hot and never had any clearance issues.

 

If it's for the roadster in the lead pic, I feel you are over thinking things. It's a simple little roadster , keep it simple and functional without adding complications.

 

Another thing you need to know is that the hub behind the fan on a fan mounted generator came in several lengths. The '32 was about 4 inches and they got shorter until the '37-'39 fans were about 3/4 inch. I think I may have some pictures if you would like one.

Charlie Stephens

 

Go 8 volt and set regulater to 9.5 volts and you get good crank and every thing else will work fine with no alterations


Sent from my iPad using Tapatalk

 

Yes, why fix the electrical system when more voltage is almost as good as a cure?
This subject has been covered before. If you want blown out light bulbs, an overheated coil, burned out points, and a red-headed stepchild electrical system, then by all means find the elusive and rare 8v battery and put it in.