More 12 Volt questions

[steveplym]

Alright I've just about made up my mind I want to convert the car to 12 volts.

Here's a couple questions I wanted to know the answer to.

What do I do about the fan belt? Can I get a GM alternator with a wide belt or how did you guys solve that problem.

Can I run my stock ignition with a 12 volt coil? I know you can use a ballast resistor, but could I avoid that by just using a new coil?

How long will my starter last? You guys running 12 volt with the original starter seeing any problems or will I need to have my starter rebuilt for 12 volts?

[teardrop puller]

get the pulley here

http://www.speedwaymotors.com/p/1868,958_GM-Alternator-5and8andquot;-Wide-Belt-Pulley-Plain.html

kai

[steveplym]

get the pulley here

http://www.speedwaymotors.com/p/1868,958_GM-Alternator-5and8andquot;-Wide-Belt-Pulley-Plain.html

kai

Thanks for the link!

[oldmopar]

Here is a few links I have found that have some good 6-12 volt information and may answer some of you questions

http://www.oldengine.org/unfaq/six12.htm

http://www.classictruckshop.com/12volt.php

http://www.film.queensu.ca/CJ3B/Tech/SixVolt.html

http://www.oldengine.org/unfaq/10si.htm

[greg g]

I ran a narrow belt with no problem on a 52 Plymouth years ago. Just yse whatever belt fits in the alternator groove.

[steveplym]

Alright I've reviewed the links above and searched the internet for more info, but still haven't quite got an answer to all my questions. I'm still wondering about ignition. Can I just buy a 12 volt coil and wire it correctly? No need to change the condenser or points right? Will the horn relay handle 12 volts or will I need to replace it? Not sure where I would find a 12 V relay that would fit my P-15.

Sorry about all the questions, but I like to plan out everything and weigh the cost before I jump in.

[Phil Martin]

I ran 12 volts on my truck for 6 years. Without a resister in line between coil and dist points won't last long. you do need 12 volt coil. Starter and horn never gave any trouble. Use a voltage drop for wipers, heater,etc. Change all bulbs to 12 volt. Used a 1 wire alt belt was not a problem.

[greg g]

coils are coils unless they are labeld 12 V internally resisted. Your stock coil with a ballast resistor will be phine.

[steveplym]

coils are coils unless they are labeld 12 V internally resisted. Your stock coil with a ballast resistor will be phine.

Where can I get a ballast resistor? I assume most parts places have them. Does it need to be connected in series between ignition and coil or coil and distributor?

[Don Coatney]

Where can I get a ballast resistor? I assume most parts places have them. Does it need to be connected in series between ignition and coil or coil and distributor?

What do the above links say about this question?

[steveplym]

Whoops, must have missed that. Thanks Don.

[Plymouthy Adams]

be sure you get the right resistor for the coil you want to use....also if you want to run without a resistor you can get the internal resistance coil (normally 3.7 to 4.3 ohms if memory serves me correct..I never use this device)

there are two basic resistors to keep in mind..one is fixed, the other is positive temperature coefficient...

use the fixed value for constant voltage in at the primary of the coil for constant value secondary high voltage...these are generally matched to the impedance of the coil you are using...this is to protect the coil from overheating and will aid in longer points life..this will be connected in series from the run ciruit of thie ingintion switch to the (+ ter if neg gnd and the - term if positve gnd) the start circuit is direct 12 volt suppy to the same terminal only when in start position of the key switch. Approximately these values are 1.5 but again..you may need a 1.2 through the 1.7 range..the counter man should MATCH the resistor to your coil...

The positive temperature coefficient resistor is one that has a a lower value in the vicinity of .6 ohms and thus the voltage to the coil will be higher creating a higher secondary spark when the engine is cold...this resistor will increase in value to approx 1.5 limiting the input volatge and thus will allow the coil to continue running cool while providing you a hotter spark during engine warm up. This resistor will not need the by-pass wire for start up..

[steveplym]

be sure you get the right resistor for the coil you want to use....also if you want to run without a resistor you can get the internal resistance coil (normally 3.7 to 4.3 ohms if memory serves me correct..I never use this device)

there are two basic resistors to keep in mind..one is fixed, the other is positive temperature coefficient...

use the fixed value for constant voltage in at the primary of the coil for constant value secondary high voltage...these are generally matched to the impedance of the coil you are using...this is to protect the coil from overheating and will aid in longer points life..this will be connected in series from the run ciruit of thie ingintion switch to the (+ ter if neg gnd and the - term if positve gnd) the start circuit is direct 12 volt suppy to the same terminal only when in start position of the key switch. Approximately these values are 1.5 but again..you may need a 1.2 through the 1.7 range..the counter man should MATCH the resistor to your coil...

The positive temperature coefficient resistor is one that has a a lower value in the vicinity of .6 ohms and thus the voltage to the coil will be higher creating a higher secondary spark when the engine is cold...this resistor will increase in value to approx 1.5 limiting the input volatge and thus will allow the coil to continue running cool while providing you a hotter spark during engine warm up. This resistor will not need the by-pass wire for start up..

Which one do you recommend Tim? or what has worked best for you? If I get a coil that is has the internal resistance will that make my points wear quicker? Thanks for the info Tim.

[Plymouthy Adams]

Steve this is your call..life of tune up is main aspect...as long as the resistor matches the coil impedance...however with the stock engine you will want to stay within your original voltage levels of the flattie as built...the value of 1.7 would be the better choice...as you go down in resistance the applied voltage will go up..keep in mind that this balance of input voltage is porportional to the value of the condenser rating with in the distributor (think pitting burnt points here)..changes here will continue to make other changes in the system..that is also why you should take the alternator you are using into consideration as the output voltage here is the determining input to the coil..this will allow best operation with consideration to stock replacement points/condenser

I based the 1.7 on a 13.2 voltage ouput..you should really do a bit of math before making your final decision..some will argue that this is not worth mentioning..and basically they could be close to right except for point life and possible condenser failure and if you later went to pertronix..the successful operational life or possible immediate failure would be totally reflected by the input voltage you have at the coil...this is the number one killer to the Pertronix system...I will not however go into this as I care not the argue the point to their advantage....

[steveplym]

Thanks for the info Tim. It is really appreciated.

[austinsailor]

get the pulley here

http://www.speedwaymotors.com/p/1868,958_GM-Alternator-5and8andquot;-Wide-Belt-Pulley-Plain.html

kai

Darn, I found this one day late. I just machined my old pulley to fit the alternator yesterday. Would have been simpler to just buy this one. I've looked for a 5/" pulley for this thing for a month. Why does it always work this way??

[jimwheeldon]

One of my hot rod mags says you cannot rig up a 6 volt positive ground radio to work with a 12 volt system...Anyone found a way around this? I'd love to have a hidden updated stereo and still keep the original one funtional.

[martybose]

One of my hot rod mags says you cannot rig up a 6 volt positive ground radio to work with a 12 volt system...Anyone found a way around this? I'd love to have a hidden updated stereo and still keep the original one funtional.

I'm beginning to think that they are right. My 802 worked fine on 6V positive ground and 6V negative ground (when I installed my first 6V alternator), but I haven't been able to make it work once I switched to 12V negative ground. I bought a 12V to 6V convertor, but no joy.

I'm pondering an internal update to a 12V radio for the future.

Marty

[Frank Elder]

I have a good working radio and as I am staying the course, 6 V, when the need for fm strikes me[or cd] it is simple enough to turn on my portable player sitting in the car.