How would a 8 volt battery effect a 6 volt starter bendix? I am trying to get a better starter rpm speed
I read your question as damage. 8Volts and 12 volts should spin it a little better but 6 volt should do the job on a good starter.
Are you using 6 volt cables and not small diameter 12 volt cables? Do you have a really good ground strap? Have you checked Every connection to be sure that it is clean, shiny and tight? Is your battery in good condition? Starter in good condition? Starter switch making good contact?
The engine really does not need to revolve quickly in order to start. My coupe is 6 volts and turns over fast enough to start. My touring is a hand crank only and it starts without a need for fast revolutions.
Could the underlying issue be simply the need for a good engine tune up?
After your 8 volt battery runs down to 6 volts, how will you recharge it to 8 volts with a 6 volt generator?
Please keep us posted and good luck with your project. Bill
6 volt starters never really spun fast. I would suggest your checking for a clean & bright metal grounding of the starter screws or even adding a "OO" guage cable with flat terminal ends from the starter mounting screw direct back to the ground strap mounting on the frame at the battery. Clean metal connections are best and eliminate problems. Good luck and post your result. Thanks !
I cannot speak to the Model T as I am a newbie to this hobby, but I do have a 1942 WWII jeep that is6v negative frame ground system. Many of those jeep owners have installed an 8v battery for various reasons with no ill affects.
I do know from experience that the grounding of the system is priority No. 1. Correct diameter or gage wire, clean ground connections and a good quality starter switch. The engine still seems to turn a little slow when compared to modern vehicles, but starts every time the first attempt. And I have left mine 6v looking for the most CCA's i could in the price range without going nuts with an optima battery. $80 battery Group 2 from O'Reillys auto parts.
My model T I purchased a 6v battery from Tractor Supply, but have got the engine to the running point yet. Still cleaning and painting.
A good engine and good starter with the correct battery cables good starter switch and good ground should start just fine on 6 volts. I don't think 8 would cause great damage to the bendix but you might have a problem finding the correct charger if you need to charge the battery before starting the car. Most chargers are made for 6 or 12 volts.
If your T's ignition is in order as well as the carburator, Steve Jelf have made this video, that shows how fast a proper tuned Model T must be reved for starting:
There's a persistent superstition that a Model T engine has to turn fast in order to start. Here's how fast it needs to spin: https://www.youtube.com/watch?v=3pv6HWWOGYA
There are reasons I would consider valid for more volts (12), but starting isn't one of them. Eight volts for starting is a Band Aid sometimes applied instead of fixing what's wrong.
If you're starting on MAG, then the engine does need to turn fast enough to fire the coils. Here's how that looks: https://www.youtube.com/watch?v=b5ycpdfIjDo
Two heads with a single thought.
Richard I use 8 volts on three of my Ts.Better turn over and brighter lights.I use a 8 V. regulator (diod) from Langs. I have 12 V. in one T and don't like it.. Don
I've used 8V for seven years, no blown globes, starter or charging problems, din't change the cut out, still an old Ford one, charging is by amps not voltage.
How do modifications for higher compression--domed Pistons, Z-head or 8-1 head affect starting with 6 volt battery?
Thanks guys for all the advice...........
Wilbur, I think they would have zero effect when starting on BAT. As long as the battery is buzzing the coils, speed shouldn't matter. Starting on MAG you need to turn the magneto fast enough to buzz the coils, so speed does matter to some extent there. But who starts a starter-equipped car on MAG?
I'll tell you what I did on a couple of my cars, to address the grounding problem. If you ground your battery to the frame, then you're relying on the ground transferring through rusty joints, old rivets, and a tortuous path to the starter. Run a ground wire directly from battery to a mounting bolt on or at the starter. You'll be pleased with how much faster the starter will turn the engine.
Of course, it also relies on using the correct size cable, the starter has to be in good condition, and so forth...
The cars weren't hard to start when new, and 6 volts worked fine. It's the years and changes and wear that make people assume "oh, they were all like that...."
I realize the people that are there, (8 volt system), are all for it but if you've got a 6 volt system in place the $ is better spent on improvement/repair of that system. I doubt 2 volts is going to make a huge difference any way. Plus, at least around here, 8 volt stuff isn't exactly rare it's non existent. As mentioned it isn't the speed it's an engine in reasonable condition with a good fuel & ign. system.
Since all automotive bulbs are tungsten filament bulbs then despite statements here to the contrary, those types of bulbs are very sensitive to overvoltage when it comes to bulb life expectancy. A typical 6V bulb for automotive use will have its rated life stated at about 7V since that is the charging voltage of a typical 6V system. There are no common nominal 8V bulbs made for automotive applications but to properly charge an 8V battery the charging voltage will be around 9.3V and that voltage when applied to a 7V tungsten filament bulb will reduce the life of that bulb to about 3.3% of its normal life at 7V. Now if the charging voltage is not enough to charge the 8V battery then the battery will have a short life while the bulbs will only have a shortened life to about 20% of normal. Assuming the reason for the 8V battery in the first place is that the wiring, switches, connectors, and cables are junk then it stands to reason that the bulbs may not be getting anything like full voltage so bulb life might be longer but of course light quality and briteness could be anything.
For the least amount of future headaches I would always recommend just fixing the various parts and staying with 6V battery.
Just adding my 2¢ to this. My '26 Fordor came from the last owner with an 8-volt battery and modern cables. I switched to a 6-volt battery and 00 cables built by a local truck shop. The starter cranks noticeably faster with this setup. And, no worries about light bulbs any more.
Aw. Go ahead and upgrade.