Six volt to 12 volt, I know why now

[oldford]

Purchased a 32 ford and the 6 volt had been changed to a 12 volt system. I really did not want a 12 volt so I installed a 6 volt battery to see what engine would do. Engine would barely turn over. With the 12 volt it spun it like a top. So guess I will keep the 12 volt.
You guys said the starter will take the 12 volts but the bendix needs to be stronger. Can someone send me a brand and part number of one I should use. thanks

[32phil]

Your B truck was originally 6 Volt positive ground.
We have a Model B with a Cragar head and higher than stock compression. It's wired as a 12 volt negative ground using the original Model B 6V starter.
After about 3500 miles the B starter drive is fine. When the starter is engaged it hits a lot harder than 6 Volt but so far so good.
We also have several later flathead V8s using 12 Volt and original starters/Bendix drive all so far so good.
We always have a few spare parts including a Bendix drive and hand tools in the cars.
Breakdowns happen. Over the years I have changed fuel pumps, fan belts among other things. Just adds to the adventure.

[alchemy]

I have been using an old original bendix on my sedan with 12 bolts for almost twenty years. About 10,000 miles. No problems yet.

[rockfla]

IF you have a 12V battery AND the matching 12V battery cables, your results are NOT a valid reason OR indictment of the 6V system...Yes 6V is half the volts of a 12V system, obviously, BUT 6V systems are TWICE the Amps of a 12V system so the wires need to be bigger to handle the amp load on them!!!! Hence, most likely WHY it spun over very slowly.

[Seth Swoboda]

With all due respect, Ford did not send a new car or truck out with a 6v system that wouldn't turn the engine over. Yes, 12v will spin it faster. If you have a good ground and the proper 6v cables, your engine will start on 6v.


For example, my '37 Ford is 6v and it starts very well. I have good grounds, good cables and I use a 6v Optima battery. My ignitions system is also set up well. The distributor was timed on a distributor tester. New cables and wiring harness.

[oldford]

Sponsored Links (Register now to hide all advertisements)

Do not know anything about the engine or car. I brought it sight unseen because I was giving a very good price. The engine maybe hard to spin due to being rebuilt. Every time I get an engine that I do not know history I drop the oil pan. The engine looks brand new inside, rods and pistons and walls. So it either has been redone or a replacement engine with few miles. Since pan is off I plan to plastic gauge the bearings. The teeth on the flywheel look good except for 5 or 6 inches. It's working so not going to replace ring. To much work.

[tubman]

If everything else looks as good as you say, I'd skip the Plasti-Gage bit. This sounds like an "If it ain't broke, don't fix it" situation.

A 6 volt Optima (perhaps in a faux case), the proper battery cables, and attention to connections and grounds are more than you need to start that engine.

You should also make sure the starter is in good shape; I replaced a perfectly good Optima once because of overly worn brushes in the starter. I'd be more concerned about the marginal teeth on the flywheel, but not that much.

[flathead48]

On 6 volt starters used in 12 volt systems , convert the coils to 12 volt with a 3rd coil being a shunt coil. Eliminate the slamming of the drive without loosing starting power.

[Seth Swoboda]

I have had rebuilt engines that were hard to turn over on the first attempt. However once I got it to spin a few times and start. The engine was loose enough to start with no problems from then on.

[petehoovie]

Originally Posted by flathead48

On 6 volt starters used in 12 volt systems , convert the coils to 12 volt with a 3rd coil being a shunt coil. Eliminate the slamming of the drive without loosing starting power.

[oldford]

Originally Posted by flathead48

On 6 volt starters used in 12 volt systems , convert the coils to 12 volt with a 3rd coil being a shunt coil. Eliminate the slamming of the drive without loosing starting power.

That sounds like a good idea. Can any auto electrical shop do that.

[flathead48]

I would think so. Old Ford

[Gene1949]

You can do it yourself. It takes about 20 minutes and some basic hand tools to make your 6 Volt Flathead starter into 12 Volt.
I bought a rebuilt starter from Rock Auto for a 56 to 61 Y block. Used the case with the field windings and the brush holder end plate with the new brushes. Cleaned up the commutator, the rotor and used the drive end plate from the 6 Volt starter. Replaced the bendix spring because that's always what breaks.
Like tubman said I would be very concerned about that 5 or 6 inches of the starter ring. Sounds to me like you have a run out problem.

[Rice]

Make sure the starter wasn't already changed to 12 volt

[34fordy]

Originally Posted by Gene1949

Like tubman said I would be very concerned about that 5 or 6 inches of the starter ring. Sounds to me like you have a run out problem.

I am not sure what the OP was referring to about the 5-6 inches. I worked on forklift trucks for many years. In our plant the engine had to be turned off whenever the driver dismounted. Some of the trucks were started more than 100 times per day so with over 30 trucks working daily much starter maintenance was required. I assumed that most engines would stop at the same place so the starter ring was worn in that spot. Needless to say when I had an engine removed I replaced the ring. Sometimes I would just heat it enough to move it enough for the starter to engage into different unworn teeth.

[Seth Swoboda]

I think converting a 6v starter to 12v is not necessary. I have two V8's using a 6v starter on 12volts and I have never had a problem. I drive my V8's more than the average person as well. Seems like a waste of time. Looking back converting a pickup and 47 tudor to 12v was a waste of time on my part...

[pbsdaddy]

For years, people have been converting from 6 volt positive ground to 12 volt negative ground. Seldom has the starter of bendix been an issue. Yes, 6 volt systems have heavier wire, therefore the 12 volt conversion will be fine. BUT, the main problem with 6 volt systems is not power, but cleanliness. Over the many years, the grounds get rusted. This results in a less than optimal contact. This results in drag. That drag the poor 6 volt battery gets blamed for. If you really want to remain stock, pull every ground and thoroughly clean them. Put it back together with dielectric grease on the contacts. Replace that 50 plus wiring with some new wires, give the ignition system a good tune and you should be ready to go. You know, like it did at the dealers, when it was originally a 6 volt positive ground vehicle. All that said, if you do convert use a one wire alternator and a new wiring harness. You'll be glad you did.