coil resistor

I need to add an external resistor to my super a so I do not burn up the points. Someone at one point told me to get a MOPAR single or something or rather. Anyone know what I am looking for? Thanks

Mark, Any NAPA or Advanced will have a generic ballast resistor in stock for around 5 bucks or less.



Andrew
Ballast Resistor

Dunno,

I've an old M that has been changed over to 12V. No resistor and it's been working hard for the past 4 years with that same 6V system in place.

Allan

Dunno,

I've an old M that has been changed over to 12V. No resistor and it's been working hard for the past 4 years with that same 6V system in place.

Allan

You want a VR-1 or VR-2 those are the part numbers for O'reilly's and they work very well and are small and easy to hide also

Here's the straight FACTS.

Coils vary in primary resistance depending upon part number, manufacturer and application. Some are as low as 0.5 Ohms, some close to 5 Ohms.

For acceptable breaker point life at a specific system voltage the combination of coil primary resistance and any added external resistance must be such that primary current (ignition "on", points CLOSED, engine stopped) is in the 3 Amp to a maximum of 4 Amps (give or take a little) range.

Less than 3 Amps will PROBABLY give a weak spark, much over 4 Amps will be tough on breaker points.

If you can, when you get your new resistor installed, MEASURE the actual primary current and see where you're at compared to that range.

NOTE... besides different resistance VALUES, ignition resistors may be either fixed resistance or "PTC" (positive temperature coefficient).

With FACTORY systems, generally a FIXED resistance is used with systems that have a "starting bypass" (a separate terminal on the starter switch or solenoid that provides full battery voltage to the coil during cranking).

For FACTORY systems NOT using a "starting bypass", a PTC "ballast resistor" is used. When the ignition is switched "on" the resistor has a relatively low resistance to aid in starting, then it's resistance quickly drops to a higher value as it heats up to prolong point life and cause less heating of the coil.

NAPA, Standard Ignition, BW, etc., have parts guides that will show the resistance for a given part number and whether it's fixed or PTC.

Finding a counterman who is willing to grab that guide and have a look is another matter.

Also, there's "true" 12 Volt coils on the market that have enough primary windings so that no external resistor is needed. NAPA IC-14SB is ONE example of such a coil.

A common one is the NAPA ICR-13 that is rated as a 1.8 ohm resistor.

It will work fine with just about any coil that does not have its own internal resistor.

If not sure, just take a reading across the two primary terminals. Should be 1.4 to 2.4 ohms.

If you get a reading over 3 ohms, you do NOT need an external resistor.

(quoted from post at 12:12:04 03/31/10) A common one is the NAPA ICR-13 that is rated as a 1.8 ohm resistor.

It will work fine with just about any coil that does not have its own internal resistor.

Click to expand...

One more vote for the ICR-13. I've had one on my 140 with Pertronix ignition for six years. But if the coil ever goes, I'll dump the resistor and put in the IC14SB coil.

I went to autozone and got a resistor for a 85 Dodge pickup with a V8. It ran without it but backfired a lot. The MOPAR resistor has a mounting hole in it, I made a tab to mount it beside the coil.