The Stovebolt Site Forums The Shop Area The Electrical Bay points and condenser for 12 volts.

What year did GM start producing trucks with 12 volt systems? Can I buy a set of points and condenser at the auto parts that are for a 12 volt system that will fit my 55 chevy 235 original 6 volt distributor? Most points and condensers look so similar that I was wondering why I should fool with reducing voltage instead of getting the benefit of 12 volts all the way and use a 12 volt coil as well?

12V started with the 55.2, but I don't think the distributor cares about voltage, other than the coil, which you must change to go 12V ... and either get an 'internally resisted' coil [will be an IC number, NAPA IC14], or you need an ignition resistor

Bill

The points and condenser don't care what voltage they're switching. We've had the discussion about reduced voltage VS internal coil resistance for years, and nobody's about to change their opinion, but it does seem significant that GM chose to use voltage-dropping resistors of one type or another on millions of cars and trucks for a couple of decades. I wonder why?
Jerry

Jerry is not the only one who wonders why "GM chose to use voltage-dropping resistors of one type or another on millions of cars and trucks for a couple of decades".

The webpage provides an Electronic Ignition Overview which includes the following facts/conjecture?

BALLAST RESISTOR

In order to increase the coil voltage at startup some ignition designs incorporate a "ballast" resistor. The resistor is switched in and out of the supply voltage to the coil. Once running, the resistor is switched in place and the coil is actually getting less than 12volts. When the engine is started, the resistor is removed and the coil gets the full 12volts. This provides a much better spark at startup to compensate for reduced battery voltage drawn by the starter. When starting a cold engine, the plugs and the air are cold, the cylinder pressure is up, and the fuel / air mixture is poorly controlled. The oil is thick, the battery is cold and its voltage drops as much as 60% because of the high current drained by the starter motor."

So it sounds like it is ok to use the rebuilt distributor I have that has new points and condenser intended for a 6 volt system. Hook up my 12 volt coil and ready to go?? Will this work with plenty of fire (inside the cylinders only)?

yes, you got it, no fires anywhere except the 'fire in the hole'

Bill

Yes, use the distributor, but wire it through the ballast resistor and the starter switch as per the document Tim posted.