VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 engine turns over slow with 6 volt

I have a 30 chevy coupe.The engine turns over so slow that it will not start with the 6 volt batt.but when I hook up a 12 volt batt to it she turn over fast and starts right up.I have cleaned the cables and the conections and even hooked the 6 volt batt.ground to where the sarter is mounted to the engine.It just will not turn over fast enough to start the engine on 6 volts.Is this a bad starter even though it starts up with the 12 volt batt.and Am I screwing other things up by starting the car on this 12 volt batt.Oh by the way this 6 volt batt.is a new batt.750 cold cranking amps
thanks chris

Hi Chris,

If you haven't already looked at this post, a similar issue was brought up on July 3:

https://vccachat.org/ubbthreads.php/topics/177108/Starter_Issue#Post177108

On my 30 coupe, one of the first things I did was replace the battery cables. Although they were both in decent shape when I bought the car, they were too small. I put in size #00 for both and that made a world of difference in starting the car. All connections have to be very clean and tight. Having the car well tuned (timing set at 18 deg. BTDC and plugs gapped at 0.40)also helps in starting. Mine will usually start in about a quarter to half rotation of the engine. You may want to check that your 6 volt battery is fully charged. I've run into cases where, even though the battery was new, it still needed some charging to bring it up to full strength.
As to any damage being done by jumping with a 12 volt, well if any lights are on it will probably burn them out. And leaving the 12 volt connected could fry the coil. But for a quick jump, you're probably not doing any harm.

Good luck,

Dan

Hello cbutcher,
Resistance within the battery cables may be a start. I have read numerous postings about inadequate diameter cables for proper 6 volt service. How about the starter? If the starter ground is faulty then your negative ground at the starter may also be faulty. Although 12 volts gets the starter to operate, it is likely the starter is the weak link with what you have described. In all cases, verify ground connections with an ohm meter. Does the engine start easily? Could the car be push started? If so, suspect the starter. 12 volt jumps-QUESTIONABLE-Remember think safety. Good luck.

regardless of the battery cables being the current problem, a 000 positive cable with a equally heavy negative should be used to avoid problems down the line. with heavy cable and clean connections a slow cranking would indicate starter problems. providing the battery is up to snuff

I keep reading about the cable size I think the batt.cables are correct for the year.Don't know for sure they were on the car when I got it.The ground cable is a flat braded cable mounted on one of the trans. bolts and the pos. cable is a round cable about 3/8 in dia.and is bolted to the starter post.Should these both be changed to what some one called 000 size cables.
thanks Chris

If your positive cable is really only 3/8" in diameter then it is way, way, too small!

the conductor it's self, not counting insulation, should be 3/8" or larger. 00 is .365", 000 is .410"

I have seen a braided ground cable that had no continuity end to end! There was hidden corrosion at the battery terminal end, so even looking good does not always make good.

I went today and got two new batt. cables for the coupe.They are made from 00 cable put new ends on the cables and took off the old cables and cleaned starter post conection and cleaned the surface where the starter bolts on.Connected the new 00 ground cable to the bolt that holds the starter to the engine and connected the hot cable to the starter post and the coupe fired right up. Turnes over with the 6 volt almost as fast as the 12 volt turn it over.I guess it just needed larger cable and better ground.
Thanks Chris

Chris,

Good to hear you've got the starting problem sorted out. Have fun, now, driving the ol' coupe around.

Happy Motoring,

Dan

There ya go! Having the right size cables does make a big difference!

It is hard to get some people to believe that good cables and clean connections are critical to 6 volt systems working properly. So many have been told 6V is unreliable and to change to 12V that way too many do it. However there are success stories like yours and the experience of many of us old Chevy curmudgeons that belie that myth.

This whole idea of "needing" to convert to 12 volt may be the most asked question about the old 6 volt cars.

It just came up last night at the weekly 1000 car cruise-in at the Beaches cruise-in at Portland International Raceway.

A guy out there told me he'd been tinkering with his deceased grandfather's 54 Bel Air wanting to get it running after 10-12 yrs or so. Knowing I also have a 54 he said he'd been told by a guy at an un-named natl parts store in order to get it to start better/faster/etc he should convert to 12 volts.

Is this True, he asked.

Nope said I!! I basically just gave him the run down, including proper cable size, I've read in here a number of times and his face lit up and a big smile and a bigger thank you. Sure is nice when a more-or-less un-mechanic guy like me can help somebody out!

All I'm saying is this dang question comes up all the time. And it's real obvious there's one heckuva lot of "miss" information about 6 volt systems out there.

Bill.

wanna bet the "guy" was 19 and the only 6 volt experience he's had is with a flashlight?

Maybe it was a guy with a high dollar "CD" player or alarm system that is 12 volts, neither of which have any real reason to be installed in a PRE- 55 Chevrolet.

AM radio and KOMA ruled the air waves, not to mention the 24 hour station in Del Rio Clint, Texas.
I used to listen to Bill Mack's open road show, midnight til 6:00AM on WBAP? 820 AM, driving my 52 Belair.

Before that when I didn't have wheels, on "Saddiddie night" it was the "Grand Ole Opery" on WSM clear channel Nashville, On the old 6 volt Philco cabinet model multi-band powered by a six volt Willard battery that was charged by the roof mounted wind-charger, in the livin' room, sometimes till daybreak!
I still think a "CD" is something that you can put your money into at the local bank.

MrMack,

There you go waxing nostalgia again.

1st radio was very primitive. You had to use headphones and juggle 3 gang condensers.

Then a great improvement. A console that had the 6-volt wet battery charged by the wind generator up on top. Then 3 67 1/2 volt "B" batteries and a 9-volt "C" (bias) battery. If the 6-volt was charged and I had completed my chores, it was to the radio to listen to "The Green Hornet", "Lone Ranger" and "The Wolfman Jack", and several more till the "A" battery was run down.

Sure did like those 50,000 watt clear channel stations. Studio in US, tower and transmitter in Mexico.

And NO!, those were not the good ol days.

OH Ray, now you are getting back to my childhood days in Missouri, when you had to tickle the chrystal with the cat's whisker!

An improved version with a loudspeaker kit!

I remember building a "foxhole" radio when I was a kid. A set of ear phones, razor blade, paper tube, wire, safety pin, a piece of wood and lead from a pencil and you were in business.

Not sure but I would think that 12 Volts would cook the coil and might damage the instrument panel gauges. A booklet on converting 6 to 12 Volts suggests using a voltage reducer between the power source and gauges. A great reference is "The Official 12-Volt Conversion Guide" by Randy Rundle. Arlington Products, (847)749-2648.
I bought the booklet because I was going to convert to 12 Volts, but after reading how the 6 volt system can be improved (heavier cable, connecting the negative ground directly to the starter). The problems I was having starting a hot engine went away.

I had a similiar problem with a new 6 volt battery--someone told me to get a INTERSTATE 6 volt battery (looks like 3 round cylinders)--it solved my problem immediately.

I also remeber building a "foxhole" radio when I was a kid.