12 volt or 6 volt starter

oldford2

oldford2

Well-known member
I have an old used starter on the engine on my stand. If I put 12 volts to it the new rebuild spins great. If I put 6 volts to it she barely turns over (good battery and heavy boosters). How can you tell the difference between a 6 and 12 volt starter?
Thanks John
 
That sounds about like a 6 volt. Even on a good day, they spin pretty slow, but they will get the motors started. 12 volts will make them hum, but if you have a motor that doesn't want to start, and you roll it over and over too much, you can burn it up. I really don't know how to tell the difference without having the insides checked out. Hugh
 
It is most likely a 6 Volt Starter.

With a fresh rebuild, the engine is stiff and the rings have a lot of drag. Until you get the engine "run in", it may be a challenge for a 6 volt starter to turn it over. If a 6 volt starter is up to spec and the battery, cables, connections and charging system are all in top condition, most of the time you can get a "fresh" engine to start just fine on 6 Volts.

Running a 6 volt starter on 12 Volts will not hurt it as long as you do not crank the engine too long at a time to keep the starter from overheating.

After you have some miles on the engine, it should start just fine on 6 volts.

Chris
 
Hi John, Just a suggestion, if you install a 6 volt starter and run a 12 volt system, keep a spair Bendix spring in the glove box... I've run 6 volt starters on 12 volts for a long time and had no trouble and I've run the same set up for a day and sanpped the Bendix spring, you just never know...:eek:
 
Re: 12 volt or 6 volt starter 19fordy

19fordy,

Thanks for the 2 articles. The first is excellent for those folks thinking about converting from 6 to 12 volts. The second article gives the actions of the starter, regulator, and generator. Great info. If only my old brain was not filled up so I could remember this info. I will save the articles and then I only have to remember I saved them.
Back to my question. I think the starter I am using may be an old 6 volt one and tired. I am going to try the starter out of our car and see what happens.
Thanks for your help. John
 
If you use jumper cables (even heavy ones) your new engine will turn over slower than correct battery cables. If you hook up the battery with correct cables with proper ends on battery it will turn over faster. The reason for this is there is a voltage drop where the jumper cables attach to the battery and to the starter and engine.
 
YES, That is correct.

Just use the 12 V Battery for the STARTER ONLY. Let the rest of the system run on 6 Volts.

Done it many times thru the years.

Chris
 
You stated that you used a 12 volt battery to start your engine and run the rest by 6 volts.I have a 31 model A and I need the instruction on how to run on this system.Any help will be welcome.
 
Morgan Smith said:
You stated that you used a 12 volt battery to start your engine and run the rest by 6 volts.I have a 31 model A and I need the instruction on how to run on this system.Any help will be welcome.
Click to expand...

Depends on whether you're asking about a 12v CHANGE-over FROM the 6v system, or a ONE-TIME jump-start of a 6v system with a 12v battery...which are you questioning about? Just to be clear! DD
 
53ash said:
That sounds about like a 6 volt. Even on a good day, they spin pretty slow, but they will get the motors started. 12 volts will make them hum, but if you have a motor that doesn't want to start, and you roll it over and over too much, you can burn it up. I really don't know how to tell the difference without having the insides checked out. Hugh
Click to expand...

Although I realize 6-volt starters do not hum as quick a 12-volt system, my 46 Coupe and 55 F-100 (both 6-volt systems) are close to behaving like a 12-v during start-ups . Both have rebuilt starters, 00-gauge battery and starter cables, with an Optima battery.
 
Some engines when rebuilt are very stiff and would require a GOOD 6v starter to turn them over. Once broken in the 6v would be no problem.
 
There are two potential areas of trouble when running 12 into 6. As stated above, the bendix spring can break, the other is that 12v slams the 6v pinion into the ring gear pretty hard, and over a period of time the ring gear teeth can wear quite badly.
 
Morgan Smith said:
You stated that you used a 12 volt battery to start your engine and run the rest by 6 volts.I have a 31 model A and I need the instruction on how to run on this system.Any help will be welcome.
Click to expand...
A Model A is probably the easiest car to swap voltage on, since there are no gauges or accessories that need changing. Put a resistor on the horn and coil, swap out the bulbs, change the battery and charging device (alternator or generator) and you are done. Probably should put a new style bendix on the starter, but the 6-volt starter will work just fine. With the parts on hand, I did mine in about an hour.
 
This may not exactly answer the question posed but if you decide to switch your system to 12 volts, the original 6 volt starter can be converted to a 12 volt by swapping the Field Coils and while you are at it change the bushings. It cost me about $87 back in '07 (for them to do it) but it would be more now. Find a good Power Systems Shop and they will do it for you.
 
I read an article years ago about taking 12V starter housing, I believe it was from a Y-Block and putting the 6V Armature in it to make a 12V starter. The only difference was the Fields that make them 12V or 6V. I did this years ago on my 51 Starter and it worked fine. Sorry I can't be more informative on the 12V model it's been about 10 years ago now.
 
Bubba.. did you ever get an answer to your question - Will a 12V starter turn the motor over on 6V? I recently had my 21-stud rebuilt and they made it a 12V engine. I asked them to put it back to 6V and he mentioned he replaced the generator, but I don't know if he replaced the starter.
 
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