6V to 12V Flat Head V8

[MelPatsel]

Can someone tell me correct and least expensive way to convert?!

[tubman]

To me, when you say "correct and least expensive" the best choice is to not do it. Make sure the individual components are in good shape and buy an Optima battery (with the optional old style case) and you're done. Most 12 volt conversions were done as a band-aid to mask other problems.

[Brendan]

make sure that you have the right size battery cables for 6 volt and a good ground.

[19Fordy]

Check this out.
https://www.vintageautogarage.com/Default.asp

Also, do a search of Converting to 12V.

[51 MERC-CT]

When I converted mine it was not because there were starting issues, but because of the electric windows.wipers, stereo, etc. that required the 12 volts.
Converting to 12 volts will not correct any fuel supply or ignition issues that you have.

[TJ]

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Just curious why you want to convert to 12 volts. depending on your problem it may or may not be necessary.

[JSeery]

Cost wise it is fairly inexpensive. 12v battery with the negative connected to ground. Reverse the connections on the coil if it has a can style coil (negative to the distributor). If not would be easiest to add one IMO. If you are using a 1.5 ohm coil you need a 1.5 ohm ballast resistor. The biggest item is the generator, need a 12v. Change the bulbs to 12v and add voltage reduces to the gauges. All the wiring is over gauge for a 12v system, so no issue there. The starter will run on 12v but will hit harder and you may want to have a spare Bendix drive on hand. The starter solenoid should be switched to a later 12v style.

[34PKUP]

Originally Posted by JSeery

The starter will run on 12v but will hit harder and you may want to have a spare Bendix drive on hand.

An what accounts for all the Bendix springs that failed while being operated on 6 volts ?

[RKS.PA]

Mel, welcome to the Early V8 part to the Ford Barn!!! Great to see you here and you'll get the best advice available from some of the best brains and experience in our hobby.


Post a question on your hard starting when hot issue and let's see what advice is given that we haven't thought of!!!


Dick.

[JSeery]

Originally Posted by 34PKUP

An what accounts for all the Bendix springs that failed while being operated on 6 volts ?

12v on a 6v starter spins up a lot faster and pulls the bendix in harder. Some folks run them this way for years with no problems. But, the starter is most likely old and well used and the extra torque can break the bendix. Carry a spare bendix or convert to a 12v starter.

[JSeery]

Double post

[34PKUP]

Originally Posted by JSeery

12v on a 6v starter spins up a lot faster and pulls the bendix in harder. Some folks run them this way for years with no problems. But, the starter is most likely old and well used and the extra torque can break the bendix. Carry a spare or convert to a 12v starter.

To repeat my question , " An what accounts for all the Bendix springs that failed while being operated on 6 volts ?"

[51 MERC-CT]

Originally Posted by 34PKUP

To repeat my question , " An what accounts for all the Bendix springs that failed while being operated on 6 volts ?"

Good question.
I know for a fact ( not anecdotal ) that on the Fords that I have owned over the years there have been a few Bendix failures while being operated using 6 volts for power.
On my current 12 volt powered vehicle with 35K+ miles using the original
6 volt starter, to this point there have been zero Bendix failures.

[JSeery]

Originally Posted by 34PKUP

To repeat my question , " An what accounts for all the Bendix springs that failed while being operated on 6 volts ?"

Sorry, my speed reading was a fail! No idea really, maybe someone else can provide some insight. My guess would be the springs see a rough life and live in a bad environment.

[Chuck Sea/Tac]

In 28 the first shafts were 1/2” then went to 5/8” and the bolts on the Bendix spring went from 5/16” to 3/8”. So they were a little under engineered. Don’t know what size the V8 starter shaft or Bendix bolts are. On my model A every couple of years, I replace the bolts and spring. I have had them break. This is on 6 v. So if 6 volts is hard on the Bendix, then 12volts on a 6 volt starter winding, is really hard on them.
I do drive my car a lot.

[chap52]

Originally Posted by 34PKUP

To repeat my question , " An what accounts for all the Bendix springs that failed while being operated on 6 volts ?"

Torque. You will notice the difference in the sound of that 6 volt starter activated with a 12 volt charge.
My 6 volt starter lasted years before breaking a bendix spring. I also experienced that the ring gears over time, about 8 years was jolted enough to slip on the flywheel and wedge against the housing enough to stop the engine from turning when I tried to start it. I attribute this to the hundreds of "jerk" starts from the 12 volt defibrillator on the 6 volt starter.
Solution, I replaced the starter with one designed to use 12 volts. No complaints, just a learning experience.

On the conversion I would go with a one wire 12 volt alternator with built in voltage regulator. That eliminates the purchasing the additional 12 volt regulator.

Enjoy the adventure, and if YOU want 12 volts, go for it. Chap

[chap52]

Torque creates a lot of added stress on the bendix.
You will notice the difference in the sound of that 6 volt starter activated with a 12 volt charge.
My 6 volt starter lasted years before breaking a bendix spring. I also experienced that the ring gears over time, about 8 years was jolted enough to slip on the flywheel and wedge against the housing enough to stop the engine from turning when I tried to start it. I attribute this to the hundreds of "jerk" starts from the 12 volt defibrillator on the 6 volt starter.
Solution, I replaced the starter with one designed to use 12 volts. No complaints, just a learning experience.

On the conversion, I would go with a one wire 12 volt alternator with built in voltage regulator. That eliminates the purchasing the additional 12 volt regulator.

Enjoy the adventure, and if YOU want 12 volts, go for it. Chap

[glennpm]

Hi Chap,


Could you please tell me what you used for the 12V starter?


Thanks

[Mike51Merc]

Originally Posted by 34PKUP

To repeat my question , " An what accounts for all the Bendix springs that failed while being operated on 6 volts ?"

I'm pretty sure nobody has collected data on the subject, so here's an anecdote or two:

I have a '51 Merc running 6V.
My buddy has a '51 Ford running 12V.
My buddy has gone through about 5-6 Bendix drives in the last ten years. I haven't replaced any.

My theory is that the 6 volt starter essentially runs at twice its intended speed, while an actual 12 volt starter will run at a lower speed.

It's like putting a 6V light bulb in a 12V supply, compared to putting a 12V bulb in a 12V supply.

[chap52]

Glenn, I believe that I used a Forn 8N 12 volt tractor starter.
I got it from a Shop in Kentucky, long ago. I recently sold truck and the receipts went with it.

Here are some on E-Bay. Chap

https://www.ebay.com/sch/i.html?_nkw...2+volt+starter