1954 dodge royal 12v conversion help

[1954royalhemi]

has anyone done a 6v to 12v conversion on a 54 royal? I just purchased this vehicle, and the past owner did a partial conversion (if you can call it that) and it's sketchy. He said he did it because he could not get a new generator, but I don't believe that. Anyway, the car starts and runs fine, but stalls when in gear when i hit the brakes. Only the clock light comes on when I turn the headlights on, and the glove box lights work all of the time. Brake lights work, just very dim. nothing else. He installed a "reducer" from the battery, and when you jump the 2 terminals, the horn will work. Just not sure if I should start fresh and convert or buy a new generator and put back how it was. Any help is appreciated.  Also wondering if changing the wiring harness can be done without having the interior stripped out. Thank you. 

[Andy J]

I changed over a '54 Dodge p/u many years ago. I changed the generator,voltage regulator,and all the bulbs.I don't remember doing anything to the gauges,oil pressure and ammeter didn't need anything.Temperature and fuel gauges were a little off,if I remember correctly.I didn't change the starter as it was dragging on 6v,but the 12v pepped it right up. Didn't change the horn,either.

 

I would imagine your Dodge Royal will be more complicated than a p/u.For what it's worth,I would leave it 6v as designed,for 6v worked just fine back in the day.I'm sure plenty of others will disagree.

[Matt Harwood]

Trying to reverse-engineer someone else's half-arsed work will be an exercise in frustration. If you have unlimited time, you might be able to do it, but my recommendation (and that of a majority of users here, I'll wager) will be to get a new, correct wiring harness and start over from scratch and put it back to factory spec. That way all the diagnostics and diagrams in the factory shop manual will be helpful instead of worthless. Troubleshooting in the future will be easier, and you won't have to track down "ghosts" in the system caused by stray grounds, bad connections, loose wires, and inadequate wire gauge. It's a bit more expensive, but doing it right the first time is always the shortest, most economical course of action. You already know what you have to do, so I'm just  confirming that it's the right choice.

[Rusty_OToole]

Do you have the old generator or can you get it off the previous owner? If so, take it to an auto electric shop and have it rebuilt. If not you will have to buy one. The auto electric shop may be able to help, or Ebay, or somebody on this board may have one.

Then change everything back the way it is supposed to be. Is the voltage regulator still in place? No doubt you will need a battery. The Optima type is recommended if you plan on keeping the car.

You may need a wiring diagram, a factory repair manual is a good investment, it will pay for itself many times over on this and other jobs.

[Grimy]

The Dodge was originally 6V POSITIVE ground, and most likely the half-axxed conversion to 12V was NEGATIVE ground--so be careful and follow a factory wiring diagram explicitly.  I like to have wiring diagrams blown up at an office supply store to 11x17 size, and have about 6 copies made.  Buy a pack of highlighters in four different colors.  Use one sheet/copy exclusively for lighting, another for ignition, another for starting and generating, etc.  Use a different highlighter color for each wire--makes it very easy to follow on the large scale 11x17 pages.

[keithb7]

I am generally not a supporter of 6V to 12V conversions as my old flathead 6 engines start and run fantastic on 6V.

However, does the V8 hemi often struggle with only 6 volts to crank it over? I have never owned one so I am only hypothesizing.

8 quantity higher compression cylinders. Overhead valves. Larger engine displacement . I imagine there is no room for anything other than perfection of the ignition & related electrical system, fuel delivery and state of engine tune. Otherwise you'll drop the 6V down quickly and there will be no starting. Colder temps. Weaker batteries. Carb heat sink and related issues. Incorrect timing of spark. Valve seal-ability. Fuel pump performance. Choke or not? And much more can lead to harder starting issues. I can't see a 6V equipped V8 tolerating much of this for long

[Grimy]

1 minute ago, keithb7 said:

I am generally not a supporter of 6V to 12V conversions as my old flathead 6 engines start and run fantastic on 6V.

However, does the V8 hemi often struggle with only 6 volts to crank it over? I have never owned one so I am only hypothesizing.

8 quantity higher compression cylinders. Overhead valves. Larger engine displacement . I imagine there is no room for anything other than perfection of the ignition & related electrical system, fuel delivery and state of engine tune. Otherwise you'll drop the 6V down quickly and there will be no starting. Colder temps. Weaker batteries. Carb heat sink and related issues. Incorrect timing of spark. Valve seal-ability. Fuel pump performance. Choke or not? And much more can lead to harder starting issues. I can't see a 6V equipped V8 tolerating much of this for long

They worked pretty well new, Keith.  It was really A/C that and other major power draw accessories that required the companies to go to 12V.

[F&J]

25 minutes ago, keithb7 said:

does the V8 hemi often struggle with only 6 volts to crank it over? I have never owned one so I am only hypothesizing.

Yes, when it's zero F or 10 below F and you need to be at work by 7am or get fired?  The old timers told me 50 years ago about needing an 8v battery on those aging Chryslers here in New England.  Most every blue collar "used car" sat outside at night, not in a modern heated attached 2 car garage.  

 

 

[Bloo]

34 minutes ago, Grimy said:

They worked pretty well new, Keith.  It was really A/C that and other major power draw accessories that required the companies to go to 12V.

 

That and GM's desire to save money on wire. It was the right decision in the long run as the horsepower race heated up, and engines got bigger and compression got higher. I doubt anyone suspected in the early 50s that would turn out the way it did.

 

12V systems were nothing new. They existed in the teens and 20s, various models of Hupmobile, Studebaker, and Dodge come to mind. They were used on some big trucks and buses throughout the whole 6V era.

[keithb7]

How about a single coil trying to keep up with 2 extra cylinders in a V8 compared to a 6. Also higher compression ratios means harder to jump the spark plug gap. 8 cylinders means less dwell time. Less distance between the adjacent points lift cam peaks. A larger voltage differential between the two battery posts means more pressure to move the electrons. In theory, likely meaning more electrons will soak and saturate the ignition coil in less time, when compared to 6V.  A higher-voltage charged coil collapses, creating a higher secondary voltage to jump the spark plug gap. Which is harder to do under higher compression pressures within the combustion chamber. Again I am hypothesizing. However it seems logical to me that a V8 overhead valve engine with higher compression ratios would benefit from a 12V ignition system compared to a 6V system. Air conditioning and more powered options aside, they probably had to up the voltage to 12V for a number of reasons indeed.

 

Just a guess.

Edited October 29, 2022 by keithb7 (see edit history)

[1954royalhemi]

2 hours ago, Rusty_OToole said:

Do you have the old generator or can you get it off the previous owner? If so, take it to an auto electric shop and have it rebuilt. If not you will have to buy one. The auto electric shop may be able to help, or Ebay, or somebody on this board may have one.

Then change everything back the way it is supposed to be. Is the voltage regulator still in place? No doubt you will need a battery. The Optima type is recommended if you plan on keeping the car.

You may need a wiring diagram, a factory repair manual is a good investment, it will pay for itself many times over on this and other jobs.

no, I'd have to purchase one. He didn't do a whole lot of re-wiring other than under the hood where I can see. i do have a wiring diagram and can follow what was done to an extent. Voltage regulator is still in place. 

[alsancle]

5 hours ago, Matt Harwood said:

Trying to reverse-engineer someone else's half-arsed work will be an exercise in frustration. If you have unlimited time, you might be able to do it, but my recommendation (and that of a majority of users here, I'll wager) will be to get a new, correct wiring harness and start over from scratch and put it back to factory spec. That way all the diagnostics and diagrams in the factory shop manual will be helpful instead of worthless. Troubleshooting in the future will be easier, and you won't have to track down "ghosts" in the system caused by stray grounds, bad connections, loose wires, and inadequate wire gauge. It's a bit more expensive, but doing it right the first time is always the shortest, most economical course of action. You already know what you have to do, so I'm just  confirming that it's the right choice.

You can close the thread. This is the best advice you’re going to get.

[Bloo]

2 hours ago, keithb7 said:

How about a single coil trying to keep up with 2 extra cylinders in a V8 compared to a 6. Also higher compression ratios means harder to jump the spark plug gap. 8 cylinders means less dwell time. Less distance between the adjacent points lift cam peaks. A larger voltage differential between the two battery posts means more pressure to move the electrons. In theory, likely meaning more electrons will soak and saturate the ignition coil in less time, when compared to 6V.

Except that most of them don't run on any more voltage than they did with 6 volt systems. There is a ballast resistor (or resistor wire) that cuts the voltage down to about 7.5V, which is about the same as a 6v coil gets when the generator is running.

 

There is one advantage though, and it is called a starting bypass. On most 12v cars, the resistor is bypassed during cranking. This is a real advantage because the voltage of the whole system voltage gets pulled way down on any car while cranking. It is worst on a compression stroke of course when the starter load is highest, and that is exactly when you need a spark. On 12v cars with a bypass, the coil voltage goes higher instead of lower while cranking. This is the only major advantage of a 12 volt system I can think of, and most 12 volt conversions don't bother to implement it. In fact, out of all the 12 volt conversions that ever passed through my service bay, exactly none had it until I got hold of them.

 

The disadvantage of conversions of course is that a bunch of stuff usually doesn't work afterwards, and the guy doing it thinks he has done the hard part by making an alternator bracket. "But it worked before" is something I have heard a lot. Just about anything can be done if you have the persistence to see it through, one problem at a time. There is usually at least one leftover though. I never had a single 12V conversion land in my bay with 100% of everything (gauges, accessories, heater, etc.) working. Some guys have to change them over to 12v because there is some 12v accessory they can't live without, like air conditioning or fuel injection or something. Having a good reason to do something doesn't make it less work though.

 

Does this car have a semi-automatic transmission? Absolutely go back to 6 volts if it does. I'd go back to 6 volt anyway personally.

 

@1954royalhemi, There's plenty of knowledgeable people around here to help, especially if you keep it as originally built, because that's what we do around here mostly. We can help you sort it out. Welcome to the forum!

 

Edited October 29, 2022 by Bloo (see edit history)

[Matt Harwood]

3 hours ago, keithb7 said:

I am generally not a supporter of 6V to 12V conversions as my old flathead 6 engines start and run fantastic on 6V.

However, does the V8 hemi often struggle with only 6 volts to crank it over? I have never owned one so I am only hypothesizing.

8 quantity higher compression cylinders. Overhead valves. Larger engine displacement . I imagine there is no room for anything other than perfection of the ignition & related electrical system, fuel delivery and state of engine tune. Otherwise you'll drop the 6V down quickly and there will be no starting. Colder temps. Weaker batteries. Carb heat sink and related issues. Incorrect timing of spark. Valve seal-ability. Fuel pump performance. Choke or not? And much more can lead to harder starting issues. I can't see a 6V equipped V8 tolerating much of this for long

 

I wonder how Marmon got a 491 cubic inch V16 to crank so easily and reliably on 6V?

 

Or Packard with their giant V12s?

 

Or the 800+ cubic inch monsters of the mid-teens that cranked reliably on 6V?

 

There's no way Chrysler sold a car that was hard to start, Hemi or no Hemi. If it started on 6V when it was new, it can be made to do so now. By necessity two years ago, I spent about two months driving my 1941 Buick daily in December and January in Cleveland. It sat outside all day and parked at night in an attached, but unheated, garage. And that OHV 320 cubic inch straight-8 with a single coil fired up every time on 6V, often with temperatures in the teens and twenties.

 

If a car built to run on 6V struggles it's because of external circumstances, not because 6V is inadequate for the job.

[1954royalhemi]

34 minutes ago, Bloo said:

Except that most of them don't run on any more voltage than they did with 6 volt systems. There is a ballast resistor (or resistor wire) that cuts the voltage down to about 7.5V, which is about the same as a 6v coil gets when the generator is running.

 

There is one advantage though, and it is called a starting bypass. On most 12v cars, the resistor is bypassed during cranking. This is a real advantage because the voltage of the whole system voltage gets pulled way down on any car while cranking. It is worst on a compression stroke of course when the starter load is highest, and that is exactly when you need a spark. On 12v cars with a bypass, the coil voltage goes higher instead of lower while cranking. This is the only major advantage of a 12 volt system I can think of, and most 12 volt conversions don't bother to implement it. In fact, out of all the 12 volt conversions that ever passed through my service bay, exactly none had it until I got hold of them.

 

The disadvantage of conversions of course is that a bunch of stuff usually doesn't work afterwards, and the guy doing it thinks he has done the hard part by making an alternator bracket. "But it worked before" is something I have heard a lot. Just about anything can be done if you have the persistence to see it through, one problem at a time. There is usually at least one leftover though. I never had a single 12V conversion land in my bay with 100% of everything (gauges, accessories, heater, etc.) working. Some guys have to change them over to 12v because there is some 12v accessory they can't live without, like air conditioning or fuel injection or something. Having a good reason to do something doesn't make it less work though.

 

Does this car have a semi-automatic transmission? Absolutely go back to 6 volts if it does. I'd go back to 6 volt anyway personally.

 

@1954royalhemi, There's plenty of knowledgeable people around here to help, especially if you keep it as originally built, because that's what we do around here mostly. We can help you sort it out. Welcome to the forum!

 

Thanks, it's beginning to look like it's the smartest option at this point. it's definitely an interesting car. never had or seen a vehicle without Park. Interestingly enough, we drove it around the block yesterday and parked it. Now it won't even start because the new alternator must not have been charging the battery, or there is now a slow drain. Ugh. Oh well. Sounds like I'm on the hunt for a new generator, 6v battery and some wire.

[TTR]

28 minutes ago, Matt Harwood said:

If a car built to run on 6V struggles it's because of external circumstances, not because 6V is inadequate for the job.

Exactly.

I have owned (and driven/used extensively) numerous vintage Chrysler Corp. cars combining both (early) Hemi engines and 6V electrical systems.

Only times I've had problems with any has been when one or more of components in them had something wrong with it/them. 

 

Whenever I've seen 6V to 12V conversions, in most cases it has been done due to either laziness or ineptness of the owner or his/her hack mechanic/rebuilder/restorer to sort out and/or understand functions of electrical components or systems adequately enough to begin with and therefor shouldn't even be working on any of it, regardless of voltage.

 

35 minutes ago, 1954royalhemi said:

Sounds like I'm on the hunt for a new generator, 6v battery and some wire.

If I may suggest, assuming this car is a "keeper", do yourself a favor and start by purchasing a copy of an OEM service manual with complete/full wiring diagrams and all service/rebuild instructions to all electrical components and read it with intentions to learn as much of it as you possibly can.

Once you feel confident of understanding all or at least basic principles of everything you've read, consider replacing the entire wiring harness with a good, OEM* type reproduction harness, then test and service or replace any individual component in the entire system.

Anything less and you're bound to have myriad of ongoing problems long into the future or at least until you do all the above or you grow frustrated enough and sell the car with the problems unsolved.

 

 

* Do yourself and your car even a bigger favor by staying away from any and all "aftermarket/universal" (usually 12V) wiring harness kits, regardless of how easy or simple their marketing efforts claim them be.

Those, like most things "aftermarket/universal", are mainly for the aforementioned lazy/inept owners or their hired hacks and usually will just cause more problems than solve, not to mention likely to depreciate the value of your car should you wish to sell it.

 

OTOH, if you don't plan to keep and enjoy the car, just forget what I suggested.

 

[Rusty_OToole]

1954 Dodge V8 was only 241 cu in, 150HP with  7.5:1 compression. There were plenty of six cylinder and eight cylinder cars of similar specs from the thirties, forties and fifties that started and ran just fine on 6 volt systems.

[Terry Harper]

On 10/29/2022 at 5:47 PM, Matt Harwood said:

I wonder how Marmon got a 491 cubic inch V16 to crank so easily and reliably on 6V?

 

Or Packard with their giant V12s?

 

Or the 800+ cubic inch monsters of the mid-teens that cranked reliably on 6V?

So true!

Back in July I had the pleasure of bringing a 964 cubic inch T-head back to life after a quarter of a century of slumber. While the six volt system didn't spin it fast compared to the a modern starter it did the job very well. with good ground and proper gauge wires and cables they work excellent. Will it spin it fast? Nope! But it doesn't need to be fast.

 

That last point is important - a six volt system requires heavier gauge wires and cables than a 12 volt system. On the big T-head we swapped out the light, over-the-counter parts store 12 volt battery/starter cables with heavy gauge welding cables. That solved the problem of the smoldering melting cables.

 

Edited October 30, 2022 by Terry Harper (see edit history)

[1954royalhemi]

13 hours ago, TTR said:

Exactly.

I have owned (and driven/used extensively) numerous vintage Chrysler Corp. cars combining both (early) Hemi engines and 6V electrical systems.

Only times I've had problems with any has been when one or more of components in them had something wrong with it/them. 

 

Whenever I've seen 6V to 12V conversions, in most cases it has been done due to either laziness or ineptness of the owner or his/her hack mechanic/rebuilder/restorer to sort out and/or understand functions of electrical components or systems adequately enough to begin with and therefor shouldn't even be working on any of it, regardless of voltage.

 

If I may suggest, assuming this car is a "keeper", do yourself a favor and start by purchasing a copy of an OEM service manual with complete/full wiring diagrams and all service/rebuild instructions to all electrical components and read it with intentions to learn as much of it as you possibly can.

Once you feel confident of understanding all or at least basic principles of everything you've read, consider replacing the entire wiring harness with a good, OEM* type reproduction harness, then test and service or replace any individual component in the entire system.

Anything less and you're bound to have myriad of ongoing problems long into the future or at least until you do all the above or you grow frustrated enough and sell the car with the problems unsolved.

 

 

* Do yourself and your car even a bigger favor by staying away from any and all "aftermarket/universal" (usually 12V) wiring harness kits, regardless of how easy or simple their marketing efforts claim them be.

Those, like most things "aftermarket/universal", are mainly for the aforementioned lazy/inept owners or their hired hacks and usually will just cause more problems than solve, not to mention likely to depreciate the value of your car should you wish to sell it.

 

OTOH, if you don't plan to keep and enjoy the car, just forget what I suggested.

 

This car is a keeper. other than a few minor scuffs here and there, the previous owner who I suspect passed away had all of the rubber replaced, glass replaced, headliner replaced, seats recovered, etc. It's in fantastic shape. There are only 2 issues I have found. The vent flap will not close as the vent lever is stuck somehow and I cannot free it and this wiring issue. I do have the Manual. It came with the car. It seems that the man who had it prior to the jackleg that I bought it from really took care of it. any suggestions on a good source for an OEM harness?

[TTR]

I’ve used numerous harnesses by YnZs Yesterdays Parts on cars I’ve restored in past 3+ decades, but I’ve also made several obsolete, obscure or not-being-reproduced 6 & 12 Volt harnesses myself from scratch for American, British & Italian cars + some antique wooden boats, including one from 1914 and couple from 1930s.

I’ve even advised/helped YnZ on several corrections for their patterns over the years/decades, but in general their products are top notch.

Others have been happy with Long Island Wiring (or something like that ?).

Edited October 30, 2022 by TTR (see edit history)

[1954royalhemi]

5 hours ago, TTR said:

I’ve used numerous harnesses by YnZs Yesterdays Parts on cars I’ve restored in past 3+ decades, but I’ve also made several obsolete, obscure or not-being-reproduced 6 & 12 Volt harnesses myself from scratch for American, British & Italian cars + some antique wooden boats, including one from 1914 and couple from 1930s.

I’ve even advised/helped YnZ on several corrections for their patterns over the years/decades, but in general their products are top notch.

Others have been happy with Long Island Wiring (or something like that ?).

Thanks! I will check them all out! 

[TerryB]

It’s Rhode Island Wiring. I hear they are good too.

[TTR]

23 hours ago, TerryB said:

It’s Rhode Island Wiring.

Duly noted.