Convert to 12V or stay stock????

B

BlueSunoco

Well-known member
Did a search and didn't really find much what I wanted to know so, do you guys stay 6V Pos. ground as original pretty much, or do you advise the 12V conversion?

I've been trying to stay stock w/ our flathead, 59AB, but it sure is getting to be a hassle starting the vehicle anymore. Have done all the usual distributor (with points) rebuild, carb rebuild, and fuel pump rebuild all to no avail. Drain fuel tank fresh gasoline makes no difference.

Time for a Petronix 6V change maybe?? Or shuck it all and convert everything to 12V??

Any advice at this time greatly appreciated.
 
You'll get a lot of grief from the purists on here that will say that 6 volt is fine. I switched to 12V and would never consider keeping anything 6v as long as I live.
 
I would try and solve the underlying problem first.

I have a 6V car and it starts great--every time.

Bad battery? My brother had a starting problem with his 1941 Buick. He had a brand new battery that turned out to be bad. On the other hand, you may change over to 12V and still have problems.
 
Same here. 12V and never looked back. I keep mine looking stock but there are a lot of excellent 12V accessories out there. I put up with 6V pos ground for a lot of years. When they switched to 12V neg we all thought we'd found Nirvana. Of course you could always go to a hand crank.:)
 
Good connections, proper cables, and an Optima. That's what I have in my '51 and I have had no problems with it. I'll bet it would start in -20 degrees. I am tempted to stay in Minnesota one year to try it and see. Nahh, that's not gonna happen!
 
I may be one of those "purest" referred to, but I have kept my 47 stock at 6 V. The lights are as bright as any of my 12 V cars, the starter spins just as fast, there is no advantage that I know of to 12 V other than you can totally rewire your vehicle with smaller wire, or, if you want to add on a bunch of 12 Volt accessories. But then you would need to convert to a 12 Volt alternator to provide the power. 6 Volt will start your 59A as well as 12 Volt long as everything else is working fine. You're starting problem is not because of the 6 Volt system. It is something else.
 
Electrical connections must be clean, especially your grounds. The cable from the
starter solenoid to the motor should be #0 or #1 gauge copper wire, with properly crimped ends. No cracks in the insulation. The grounding connections should be cleaned - no rust, grease, etc., that will act as insulation. Clean your battery posts as well. Is your 6V generator connections clean and is the generator in working order? Nick Alexander drove stock woodies across the country and back - all were 6V. And we won Dearborn awards!
Just take some time and evaluate and correct your 6V system.
 
wga said:
Electrical connections must be clean, especially your grounds. The cable from the
starter solenoid to the motor should be #0 or #1 gauge copper wire, with properly crimped ends. No cracks in the insulation. The grounding connections should be cleaned - no rust, grease, etc., that will act as insulation. Clean your battery posts as well. Is your 6V generator connections clean and is the generator in working order? Nick Alexander drove stock woodies across the country and back - all were 6V. And we won Dearborn awards!
Just take some time and evaluate and correct your 6V system.
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Likewise, I drive my 47 1000 miles per month all year round from 7° to 100° and it always starts fine if everything is working right. My most recent nagging starting problem turned out to be the starter solenoid worn out. I replaced that and was back to normal. One other time the ground strap from the engine to the firewall was loose that drove me crazy until I discovered it. The 6 V batteries I get from NAPA also don't usually last their entire predicted life. So that's always something to check.
 
Old Henry said:
Likewise, I drive my 47 1000 miles per month all year round from 7° to 100° and it always starts fine if everything is working right. My most recent nagging starting problem turned out to be the starter solenoid worn out. I replace that and was back to normal. One other time the ground strap from the engine to the firewall was loose that drove me crazy until I discovered it. The 6 V batteries I get from NAPA also don't usually last their entire predicted life. So that's always something to check.
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The battery life thing was enough to make me quit 6V. The 6v batteries available to us are garbage. You might get a little more life out of them if you use them constantly, but if they're dormant at all, they just die and wont take a charge (yes, even with the battery unhooked)

Went through 3 batteries in 3 years.
 
I too, had problems with commonly available 6V batteries. I went to an Optima in 2002. It finally died last year, so I bought another one then. I hear they had quality control problems a few years back (probably when they moved their operation from Colorado to Mexico), but those seemed to have cleared up. I have mine in one of those cases that look like a regular old battery. I( had to work on it a bit to make it fit perfectly, but only an expert can tell it's not real.
 
39topless said:
Here's some great information relative to your question. Rumble Seat was the best.
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In lieu of installing an entirely duplicate 12 V starting system as Rumble Seat suggests, I keep a charged up 12 V jumper box in my trunk in case the 6 V battery has died. I can hook it right up to the 6 V battery and start the engine without any trouble when necessary.
 
Convert to 12V and leave the 6V starter motor ( It will handle the 12V conversion fine, could spew a lot of electrical rational jargon but it works ) and as an added benefit your starter motor will run twice as fast. Faster easier starts.
 
Putting 12 volt through a 6 volt starter can and often does snap bendix springs, so be careful with that.
I do agree with the 6 volt guys. If everything is up to spec, including cable size and real clean grounds, it's a perfectly good reliable system. The biggest issue against you is the batteries, as mentioned above. Go for the optima. Never heard a bad word with them, appear to outlast everything else many times.
Martin.
PS. What model omptima you guys using?
many thanks.
 
First and foremost, fix the problem. these cars worked fine on 6 V for 70+years. Having said that, go for the 6V Optima battery. You can fit it in an old rubber battery case (lots of work ,but worth it) and everything looks bone stock and works great. The Optima will spin the starter like crazy and will hold a charge almost forever. Get a Battery Tender for long term non use.
First, fix the problem. Flatheads are famous for easy starting.
My opinion. 6v Optima 32 and 40
 
I have a number of Flatheads that are 6 volt positive ground and a few that I have converted, or that had been converted to 12 volt negative ground when I bought them. As has been said, 6 volt positive ground is fine, as long as the electrical system components and grounds are in good order. 12 volt negative ground conversions also work well and, it is easier to fine 12 volt parts if something goes awry while out on a road trip, etc. I usually try to bring extra components like generators, voltage regulators, starter Bendix springs, etc. when I go on a road trip and that applies to both 6 volt and 12 volt equipped vehicles.
 
Thanks guys. Should have given a bit more info, as Floyd said in post #18 'Original worked fine for 70 years' been trying to stick w/ that. Vehicle only used occasionally, put on fewer than 400 miles per year.

Anyway, she cranks to beat the band, original starter rebuilt professionally about three years ago. It just doesn't want to fire. Looking down the carb and working the throttle the accelerator pump is doing it's thing so it seems fuel is not a problem. Once you get it running it runs great. It's that 'once you get it running' that is baffling me! Have owned this vehicle for about 8 years and always ran very very good just this year I'm dealing with this problem.

I'll do as Ol Ron suggested this week and run a compression check.

Talked to two mechanics one a long time Ford mechanic w/ little experience w/ Flatheads the other builds street rods has worked on Flatties for years.

First mechanic (Ford dealership): 'That's a sign your engine is just tired. It's worn out. Flatheads are known to act that way.'

Second mechanic (Street Rod guy): advised ditching the 6V pos ground and converting it all over to 12V Neg. ground. Said at the least to try a Pertronix Ignitor Ignition and Flame Thrower coil for 6V he thought THAT may Light My Fire as Jim Morrison used to say!

Thanks for the responses I value all of them. If I get this critter figured out I will post the results. I've been around Model A Fords for many years and never had a problem like this. Those old girls seem to run and run:o I'm still learning on the Flathead curve! (Although our Flattie is easier to drive and run w/ modern traffic vs. a Model A)

Forgot to add, plugs are Autolites look like new, properly gapped, not oil fouled or sooty at all even have a tanish color to the porcelain-----
 
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