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Help understanding 6v to 12v swap over

B

BT73000

Member
So I have a 640 that was converted to 12V before me. The trouble I?m having is with burning points. The
system has a ballast resistor installed in the primary feed coming to the coil. The coil is a Echlin
replacement from Napa that is 12v external resistor required. The points and condenser are Napa as
well. I can check the voltage anywhere after the resistor and it is around 12v. I thought the purpose of
the resistor was to reduce the voltage from 12 to 6 to avoid burning the points? If that?s true, then I must
have the wrong resistor I?m thinking. The tractor will run in this current state, but it will quit periodically
and I have to get it back going by filing/ sanding the points. Any ideas?
 
The resistor only drops voltage when current is flowing.
Measuring it with the points open, key on is irrelevant.
If it were mine, I'd get a true 12V coil. NAPA IC14SB or equivalent
and get rid of the resistor all together. Just more connections to
corrode and cause trouble. If you've filed or sanded the points,
they probably need to be replaced too. New points do not stand
up to filing or sanding like the old ones did.
 
I agree with Royce. makes for a cleaner installation BUT , make sure the condenser is mounted tight to the plate. Better yet, replace the condenser
 

If you want to keep the napa coil you have post the napa number are ask napa to look in the back of one of their OLD illustrated catalogs it will list the resistor need for the coil application...
 
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