8V Battery on 6V 1936 Buick Special

How do you forum electrical experts feel about me using an 8 volt group 1 tractor battery on my otherwise unchanged 6 volt system on my 1936 Buick 40 Series?

My reason would be to get greater cranking power. I want to still use my stock guages, heater, clock, radio. I do have extra heavy cables on my battery.

I had my starter rebuilt and I rebuilt my engine quite a few years ago but I have been at my restoration so long that I have less than 50 miles on it. I am confident that my rebuild tolerances were correct but I wonder if my engine is simply still tight and obviously not yet broken in. So it seems difficult for the 6 volts to spin her fast enough to start.

I also want to know how bad an idea it is to use a 12 volt jump briefly to get her started.

I personally would put a 6 volt optima battery in the car. You get great cranking power from Optima batteries and they charge at the normal rate of your generator and regulator. To maintain 8 volts requires a regulator change. In my opinion, Two six volt batteries in parallell is a better option than 12 volts.

Bob Engle

Thanks Bob. Seems like I recall mention of the Optima batteries before. Good point about the voltage regulator and generator charging rate.

It is my understanding with an 8 volt battery, you will need to adjust your voltage regulator.

Never been in the position of too tight of an engine, but I've been using a 6 volt batteries on my car (1937 Special) for almost 40 years with only one problem starting the car and that was because the starter rebuilder didn't know what he was doing. The freshly rebuilt starter would barely turn the engine without spark plugs due to using the wrong brushes. I'm for trying to stay original and look for other issues before going to a bandaid fix.

Carl

Might well be worth checking out the starter again.

+1 on what Bob said. I am going to have custom battery cables made for the Roadmaster. I will be using two 6 volt Optima batteries in parallel. This will do several things for me... 1) lots of cranking power, 2) stock generator and regulator will charge properly, 3) no voltage problems with radio, gauges and lights, 4) the two Optima batteries will fit into the stock under seat battery tray with very little modification, 5) the custom cables will look good from the engine side of things.

These are just my thoughts, your mileage may vary .

Thanks. I just pulled the trigger on buying one Optima. May try a second one at some point soon. Bought the battery and a tender from Amazon at a good price.

Thanks. I just pulled the trigger on buying one Optima. May try a second one at some point soon. Bought the battery and a tender from Amazon at a good price.

I bought an Optima, about the only thing that was a pain (for the earlier cars at least) was that it was slightly too long to fit in the battery holder. I carefully filed down the two plastic lugs on the end of the battery (I only had to take a couple of MM off each side) to make it fit

I just bought a 6 volt car and the previous owner recommended an 8 volt battery. I bought a new 6 volt. How could a new car dealership even got any money from customers, or anyone to even come in the door, if those cars didn't start well? Surely they wouldn't have sold any at the Buick, Cadillac, and Lincoln price range.

If you made the bearing or rings too tight they can be reinstalled. If the piston skirts are dragging the 8 volt probably won't help.

One of the shortfalls I see on these cars that grunt and barely start is incorrectly set initial timing or malfunctioning variable timing components.

Is the initial timing set correctly? Does the breaker plate move freely? Are the mechanical advance weights free? If a cable attached to the chassis feeds back timing settings, is it in place? Is the vacuum advance tube connected to the right location and sealed? Is the vacuum advance diaphragm operational?

Each of those questions reminds me of a happy person, kind of like the banker in the 1930's who bought his second new Buick.

Bernie

Hidden Hunter: What car was it for that you needed to make slight mods to the battery to fit?

60FlatTop: I understand your point and I agree with you that if I have everything right the car should crank and run on 6 volts as it was successfully designed to do. You have given me several things to check, which I will do. But many of the checks require getting the car cranked.

Keith

Keith rereading your initial post I have a couple questions. Do I understand correctly that you put 50 miles on the car after the engine and starter rebuild (several years ago) and now it just won't crank fast enough to start? Have you adjusted or changed anything since you've tried to get it running? My thinking is if the starter started the engine after the rebuild it should start it now and it is a different problem. Quite possibly something else electrical like a bad ground, if possible pop the band on the starter and check that the commutator is clean and shiny, glazed over points, timing (like Bernie suggested), bad wire, coil. Hopefully the new battery will work, but I would suggest checking some of the basics before getting too frustrated or spending to much cash. I know it has been awhile since you've started your Buick, but even in the best of shape they don't crank quite as fast as a 12 volt system like we are accustomed to.

In regards to your question about jumping the car with a 12 volt battery I have never done it and would probably only try it if stranded without another option. That being said I have known of people that have done it successfully.

Carl

Keith,

Make shure you have big enough cables, 2/00 or 3/00. any smaller than that you will have slow cranking problems.

JB

Hidden Hunter: What car was it for that you needed to make slight mods to the battery to fit?

26 standard six - the battery holder is almost square in these but I don't know if batteries had taken on a similar shape to a modern battery by 36

My 1937 Special also cranked slowly when hot. It was amazing what a difference it made after re-cleaning all the contacts and redoing the positive cable clamp, taking the stranded end, spreading the strands, scraping them clean and carving out the clamp for a better fit. Spins fine now. I was so impressed that I did the same on my 1925 Standard. She spins better now also. While I was redoing the clutch did some other things and the cables were one.

Larry

I have occasionally used a 12 volt battery to jump start my 28 without any negative effects. So if it's still cranking slow you could try that just to get it started and then take off the jump cables and run on six volts.

Dave

I switched to a 6V Optima after having the "standard" type battery fail after one year ....twice.

To avoid having that bright red top showing, I found a black plastic container (trash can) at the discount store that had the correct inside dimensions to cover the battery (see photo) Trimmed the plastic container to size and drilled holes in the bottom for the battery terminals. Presently it is retained with a heavy duty cable tie, I do need to make a better battery tray.

I also found that Schumacker makes electronic battery charges that sense battery voltage and can be used on either 6V or 12V batteries, they also have a trickle charge setting. I have purchased several off Ebay and am very satisfied with them. You can buy the Schumacker charger for about 3/4 the price the parts people want for just a 12V trickle charger.

As I said, I bought a red top Optima 6V battery and now wanting to go ahead and buy a second one and install them both in parallel. Problem is that I can't seem to find any info at all on battery terminal fittings that will enable two cables to be clamped to one terminal. This would need to occur on both the positive and negative posts and of course these posts are different sizes/tapers. Anybody actually done this before and have any advice on type and source for the fittings to do the install? I'm thinking the short jumper cables between the same posts of adjacent batteries need to be just as beefy as the cables to the starter and the ground. So heavy duty clamp fittings seem to be the way to go but I find no such items. Help!

The clamps in my '41 Caddy originally came from NAPA, and are as heavy as my 000 cables - they have a clamp on each end, and one end also has a post. The car is not here, or I would send you a photo.

I imagine you could find these connectors where they sell RV Parts, because they use multiple 6-Volt batteries in Parallel - also for Golf Carts?

I've used both, Optima & wet cell 6V batteries thru the years. Optima was the best but had fitting problems as mentioned. On my 1933 Essex Terraplane 8, the battery was under the back seat in 1933. It was moved to a holder inside firewall by someone and used a 8V battery. The generator brushes had to be moved forward a bit or something, don't remember. Finally just used a Optimia 6V dry cell, NO acid. Also has spent a ton of dough on buying 6V batteries over the years.

NOW, my thing that works for me on a 1933 90, is a standard 6V wet cell with a battery tender. So far, 4 years and counting.