The Stovebolt Site Forums The Shop Area Engine Shop compatability of ignition components 6-12 volts

What ignition components in a 6 volt system are compatible with components in a 12 volt system?For example, can you use a condener or coil,that was originally meant for a 12 volt system, in a 6 volt system? Thanks in advance.

You can use the 12 volt coil in a 6 volt system if you don't use the ballast resistor. Points, plugs and condenser will be okay.

The 6 volt parts are no trouble on 12 volt. You just need to use a balast resistor. I use the one from a 70 roadrunner.

OK let me rephrase that. 12 volt parts are good on 6 volt. They are really the same, modern cars have a balast resistor to cut the voltage. Condensers are like 10,000 volt they block the spark so it goes to the plug.

Ok, I was little confused by the replies I got, partly because I didn't make it clear what i was trying to do, which is find out what 12 volt parts work in a 6 volt system. Now I'm curious about the coil. Just to clarify, 6 and a 12 volt system both use the same coil but the 12 volt system has a resistor? so basically I can take out a 12 volt coil and put it in a 6 volt system and have no problems because i left the ballast resistor in the 12 volt car? Thanks, and sorry about the confusion.

Jon:
You will need a 12 volt coil WITH a resistor--either enclosed or externally. (I prefer the resistor to be part of the coil myself--less wiring) All other 6 volt ignition parts are ok with 12 volt, but JUST ignition--not bulbs, gauges etc.

Yes, you can use the 12 volt coil in your 6 volt system. While they don't use the same coil, when you put the 12 volt coil in a 6 volt system, removing the resistor comes close enough to equalizing things. If you leave the resistor in the circuit, you will have lower voltage to the plugs. I don't recall the numbers from the top of my head, but you won't be too far off when you take out the resistor. Don't be afraid to give it a try, you won't hurt anything as long as you aren't running with a computer.

A 6 volt ignition system consisted of the following parts:

Wire from ign switch to coil
Ignition coil
wire from coil to points
points
condenser
distributor

When Chevy first went to 12 volts in '55, the engineers noticed that the coils and points were burning up quickly. They solved the problem by adding a resistor to the wire that went from the ign switch to the coil. This dropped the voltage down to about 7 or 8 volts at the coil, and kept it and the points from overheating.

The external resistor was then replaced with a resistance wire from the switch to coil. This wire had the resistance needed built into it, and thus eliminated the need for external resistor.

In later years, the resistor was built inside the coil. This eliminated the need for any external resistance. This "internal resistor coil" is a TRUE 12 volt coil, as it can be connected directly to the 12 volt ign switch.

When GM went to HEI in the mid '70s, the coils were redesigned to work with a solid-state trigger, different plug wires and larger plug gaps. The windings of these coils do not require a resistance, nor do they have one built-in. These coils cannot be used with points ignition, as they won't trigger correctly with points.

Short answer: I assume you're running a 6 volt system, so you don't need a resistor. Use a 12 volt coil for points ignition that does NOT have a built-in resistor. The system is already at 6 volts, so you can use your stock points and condenser.

The condenser is a special type of capacitor. It is for suppression of radio static and to reduce arcing and pitting of the points. When they fail closed-circuit, they can provide a coil a constant ground. This prevents the coil from firing, cuz the coil never "sees" the points open. If a condenser fails open circuit, it does not suppress radio noise, and the points pit and wear out quickly while running.

Good luck

chip