12 volt coil voltage

tomfg

Member
Now that my SC is running again, I decide to check the coil voltage so I don't burn up the new points. It's a 12 volt conversion, with 12 volt coil, with an external resistor.
The voltage at the distributor side of the coil, with the engine running, is about 9.5 volts.
Is this low enough so the points don't burn?
Thanks, Tom
 
Don't know what is legally right but I have a lot of hours on Case gas engines with a ballast resistor and 12 volt coil and never burn points. Surely someone will come along and say I'm wrong, but thats what I do.
 
I went to the [archives] {keyword search]converting 6volts to 12 volts then I selected YT articles instead of the Case forum,and found some of the info your looking for .good luck Chuck
 
I think your OK, I have converted several by doing the same thing and to be honest about it never checked the voltage and everything worked fine. One thing we have to remember is with the resister installed the amperage flow is really restricted and that is was does the most damage. Think of it this way, grab that coil wire when the engine is running. now we know it will give you a jolt and maybe even loosen some dental work (I;m kidding), But it won't kill you. Now that was probably 50,000 volts, but low amperage. Now what would happen if you grabbed a live 240v line, those have high amperage and we know what would happen , not good. On the same hand one can grab terminals of a good 12v batt and nothing happens. 12 volts (pressure) is to low to push amps (flow) through us that would hurt us. Sorry for the windy post, I got carried away, Rod.
 
Sorry but what you read was not true voltage since a meter is not fast enough to catch a true reading like that. To do a read you need to check the voltage 2 ways. #1 with it not running and the points closed you should read almost no volts and with the points open full 12 volts then post back what you get
 
Old, I checked the coil voltage as you suggested today. With the ignition on, I cranked the engine over by hand very slowly, and read the voltage thru three cycles of points opening and closing. The "closed" voltage varied from about
3 to 4.7 volts, and the "open points" voltage averaged between 11.5 to 11.7 volts.
Thanks, Tom
 
Ok when open that says you have battery volts or close as you should have. When closed you read voltage dropped across the coil and resister which again reads close to what you should. If you where to read it with out cranking it with the points open you should have read battery volts as in 12.3 or so but with you cranking it the voltage reading will be a bit less then battery volts due to starter draw. Same holds true as for the voltage with the point open. If you had check voltage by hand turning the engine you would have probably read 12.3 or so open and around 6 volts when closed but what you got says your just fine
 
(quoted from post at 13:08:50 12/20/12) Old, I checked the coil voltage as you suggested today. With the ignition on, I cranked the engine over by hand very slowly, and read the voltage thru three cycles of points opening and closing. The "closed" voltage varied from about
3 to 4.7 volts, and the "open points" voltage averaged between 11.5 to 11.7 volts.
Thanks, Tom

Tom, I admit to being a bit puzzled by your 3-4.7 V points closed.You should read no voltage unless the points are dirty setting up a resistance.

The points are a ground point till they switch open. Unless the contact material contains some resistance.

mEl
 
Ya I would call it good. Ya if down the road you burn up point then maybe need to dig deeper but I'll bet you do not have any problems
 

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