I have a late '26 Touring with a distributor/coil mod. The generator is a little lacklustre and I'm thinking about replacing it with an alternator. Snyder's have them in 12v or 6v and I'm thinking it could be a good opportunity to upgrade to 12v, so I'm wondering what's involved.
Off the top of my head in addition to the alternator I assume I need to change battery, coil, bulbs, - anything else? Does the starter need changing too?
There are many opinions regarding this. Here is my take . . .
I run my cars 12V negative ground as I drive them and like the ability to go pick up parts I might need. I run a stock starter with no magneto and a distributor.
Other arguments usually include "it works great as it was designed" and "keep it original"
The starter will turn and engage harder with 12V and I believe this could become an issue with the added weight of the ford magneto and poor neutral (cold oil, not adjusted right etc). I have never had a starter die on 12v. If anything dies it is usually the spring on the bendix or the bendix. It pays to find a good original.
I run 12V in my TT. You'll need to change alternator, bulbs, starter and battery. Coils will do just fine on 12V.
When I had my TT all apart I decided to go with 12V for several reasons.
1. A little more spark pep when cranking.
2. Ease of finding bulbs and batteries.
3. Brighter lights.
4. I had a 12V charger but not a 6V.
I didn't worry about the starter. It never worked anyway so I just blanked out the holes and use the Armstrong starter.
None of these reasons is justification to change for a purist. I'm not a purist.
Switching to 12 volts can cause starter and bendix issues if you neglect to retard the spark. 6 volt systems with proper cables and a good generator work fine though. (Said by someone who uses 12 volts on one car and 6 on the other.)
Here is a link from last year:
The only reason I converted to 12V was because I wanted LED's for my side lamps. All of the instructions are there.
There are purist that will argue to never convert to 12V. If done correctly, you will not have any starter problems.
I'm not entering a dog into this fight. But a recent Depot Hack acquisition had a 12v battery running the starter only. The power wire to the terminal black had a resistor in it so that everything downstream of the resistor was running on 6v such as lights, coils and horn.
The mag did not work on this hack and the magnets may or may not be on the ring gear. TBD at teardown. But I was advised that the starter or ring gear could have issues running on 12v, so we put it all back as 6v and will review the mag issue at teardown.
It is an option and is ofter debated on the WWII jeep forum that a compromise might be an 8 v battery. Consensus is that 6v generator will charge 8v battery and lamps and coils can handle 8v as well. Just another variable to add to the mix.
A good generator will charge 12volts.
My T came to me with 12 volts and has been working fine for many years of almost daily use. The starter is still 6 volt but hasn't given me any problems at all. I would not change over myself as the 6 volt system works great but my car has been working great on 12.
All very helpful, thanks guys.
I've been given to understand, by a very well respected forumite, that the geared alternator made for the Model T will just about invariably self-destruct because it doesn't have an integral cooling fan which every alternator needs. -The belt-driven alternators do have this cooling fan, so at least in that respect, they should be okay.
I have a belt-driven alternator and 12-volt system in my originally entirely non-electric '15 Touring and in my case, the alternator seems never to have done a darned thing to keep the battery charged. -I gave up on it years ago and charge the battery once a month with a house-current charger, which while not really much of an inconvenience, shouldn't be necessary at all. -Maybe it happened that the particular alternator unit I received is a lemon or the gentleman who installed the system goofed. -Either way, though an owner of such a system, I'm in no position to give it a recommendation
Deke, When a walk in comes in the shop and conversation drifts that the walk in has changed to 12 volts I am glad. I always tell them to not forget that I have plenty of Bendixes and when they fowl up their bendixes they can come and buy one of my rebuilt bendixes. Sure enough they are ALWAYS BACK looking for a bendixe. I don't want to argue if you are a 12 volt advocate, FINE, I just know what works for this shop.
Many alternators don't kick in until the RPM gets up a ways. In may cases above the relatively low idle speed or even slow cruising speed of a T. If belt driven, you pretty much need the largest crank pulley and smallest alternator pulleys that you can find. The early pans with narrow snouts don't lend themselves well to that.
I also experienced failures of gear driven 12 volt alternators in the past that did not have internal fans. It's worth checking to see if the current versions have fans.
The potential damage to the starter bendix ain't got nothing to do with not retarding the spark. It's not a kickback issue. It's a bendix slamming into the flywheel at warp speed issue.
My wife has a Farmall H that had been "Upgraded" to 12v. The bendix is not what kept failing on it, it was the bearing plate of the starter. It was just not made to stand up to what 12v would do to it. It busted 3 starter plates before we did something about it. My vote was to go back to 12 volts, but it weren't my tractor. She let someone talk her into keeping the 12 volts, but had someone do something (Shunt? whatever that means?) the starter so it won't slam the bendix out as hard. Seems to be OK now. At least she went with a generator this time rather than that goshawful alternator that kept the hood from being latched. The only external sign of it being 12v now is that stupid looking resistor hanging off the side of the coil. Yeah, I could find a 12 volt coil, but it runs, and did I mention it weren't my tractor.
So, do as you wish. Ain't my T either. It's yours. Just remember, most T "Upgrades" ain't "Upgrades" in the long run. I bet I see more posts about bad alternators on here than I do bad generators, and the bad generators are probably because they're 50 years old. Ever seen a 50 year old alternator still working? But I digress. I'm just purist. Bad thing to be nowadays on this forum.
Absolutely nothing wrong with being a purist Hal. I try to keep my '26 Coupe correct or at least adding or removing things that can easily be brought back to correct. My speedster is a totally different critter.
Actually, I'm more purist than not, i was just thinking out loud and trying to learn some stuff. I don't want to do anything I can't easily undo and I certainly don't want to cause any damage so I guess I'll stick with 6 and find a way to stop the battery draining.
BTW, a shunt is a impedance load that drops the volts down to a level that isn't causing any harm, like a ballast resistor - that much I DO know :-)
May I suggest something with more info from your latest post Deke?
Battery is draining down on it's own?
Guys, might a crappy cutout also give lackluster generator performance? Let's say for a moment Deke's generator is OK.
I haven't crossed that bridge into 6V generator land yet on the 18 and the 25 TT here.
Fall is coming and I'll step into T generators...
I put a 12V alternator on the Crappy 24 T here a couple years ago and needed to grind some of the alternator frame/body OFF on the block side so I had the room to bolt it up.
Time consuming and expensive alternative for a hand cranker but I had no generators here then. Alternators can be hard to find in stock at times too.
I was already 12 volt due to the dizzy on it also.
Sorry so wordy but I'm learning on the fly too and find this subject very interesting.
(Message edited by Duey_C on August 21, 2017)
All suggestions very welcome, thanks!
Just to give you all a bit more info, we don't run the T often - I guess we're averaging 20 miles a week or so - so it's tough to know for sure if it's draining on its own or while driving. I can say for sure the ammeter reads pretty much zero when ticking over and dips to -15-20 when I put the lights on, so I assumed the genny performance was to blame.
I don't know what a cutout is or does. Is it the circular silver box sitting atop the genny?
yes - maybe.
Fun Projects Voltage regulator looks similar.
6 volt batteries don't last and are hard to find. They go dead in 3 months without a maintainer. The car works well on 6 volts but the battery is the issue for me. I also drive my cars a lot so finding parts on the road is essential.
I routinely get more than 10 years out of 6V batteries. I am on my third battery since the late 1980's and it has more than 13 years on it. If your battery is going dead then something is probably pulling it down. A "parasitic" drain on the battery that is there all the time is probably to blame. That is not a failure of a 6V battery since ANY battery would drain in a short time if there is some parasitic drain on it. There are so few causes of that, I don't see why you can't find it - have you ever looked for it?
I don't think it's draining, I think it's not charging.
My six volt batteries also last several years (truck, mowing tractor, Model T's), and I have no trouble finding them. I don't know about the UK, but here any farm supply will have them.
10 years out of my 6V batteries here. Never had a difficulty buying one. I was told by the salesman that the same battery is used in forklifts.
I keep the generator setting low at 5A, which probably helps, and put the battery on a maintainer after use.
One of the convenient things of course, is that with a Model T the battery doesn't have to be replaced straight away when it begins to fail. Just good enough for the coils is all that's needed to start my car.
If your 6 volt batteries are only lasting 6 months something is wrong with your Model T!
Assuming you actually bought a good battery (always check them when buying new) and the charging and lighting system on your car is working correctly there is NO NEED to use a battery maintainer to keep the battery charged.
My '25 was completed in 2010, but the Interstate battery was in it a year or two before that. Every single wire in the car is new, and I'm using a John Regan regulator. The car always starts immediately. A factor many overlook in electrical systems, is the starter switch. Take it apart and check it out. You are wasting your time with a 12 volt battery.
I see it somewhat differently.
I think many new Model T owners don't know what they don't know.
When the Model T was new it was a very good and reliable car. Admittedly maintenance of the older technology design was higher, but if you followed Ford guidance you were usually OK.
After 80+ years many original Model T parts are not working properly. To correct this, you have to understand how it was supposed to work, get it right you you will be back in proper operation.
The 6 volt system used on the Model T worked very well when new, but worn out wiring, bad switches, rusted connections, a limping generator and starter cannot be properly correct by using a 12 volt battery.
I rebuild generators and starter to like new condition and in many cases the customers call me amazed at how well they work. In many cases owners observe that the starter cranks the engine like it had a 12 volt battery. The starters they send for rebuilding had a failed terminal bolt to buss bar connection.
I don't see it as a "purist" versus "non purist" debate.
"...I think many new Model T owners don't know what they don't know...."
From my perspective, I have to agree with that. One common misconception I see is that many folks seem to think that the "faster the crank turns", the quicker the engine begins running.
I am constantly amazed by "free starts" and the videos showing how some experienced T owners turn the crank ever so slowly and at the first "contact" the engine begins purring nicely.
Maybe "timing" isn't everything, but it certainly helps!
Common assumptions regarding 12v vs 6v
1. Stock engine with "low" compression
2. Stock camshaft
3. Stock ignition system