Pertronix and Ballast Resistors

[Guest Anonymous]

A knowledgeable '02 guy recently told me that the stock ballast resistor needs to be removed when a Pertronix pointless ignition is installed. This because the Pertronix has its own resistor and in combination with the BMW resistor, increases the resitance too high for solid spark, especially during starting.

I have had difficult "warm" starting for years that proper carb, timing, valve adjustment, solid compression, etc, etc will not solve. I now suspect this is related to the improper install of the Pertronix. The car starts fine cold and hot, idles well, and pulls great through out the rpm range.

Advice welcome. TIA. (PS. Yeah, I could just pull the OE ballast resistor and test the above hypothesis, but I'd like some informed feedback before a goose chase.)

__________________________

Roger

'72 Malaga

RBenson685@aol.com

[Guest Anonymous]

With stock wiring and stock coil the ballast resistor is bypassed(shorted) during starting anyway so I don't see how it could be causing a starting problem. You could just try a bosch blue coil and remove the resistor as it is only used after starting.

[Scott Sislane]

maybe your wire that runs from the starter's trigger (+) to the coil (think that's what it does) is not connected. So you're not getting the hot spark for starting. Have you checked the starter to see if you have a small wire connected to it? Stock starters have the slide-on connectors. (poor connection method) When the starter is turning, you should have +12V going straight to the coil (like Dave said) by-passing the resistor.

Or even if it is connected, poor connection? You should also check continuity between the starter end of the wire and the coil end. YOu should have 100% continuity. (no resistance)

Someone correct me if I'm wrong.

[Mike87]

From my experience and first hand knowledge, do not remove the ballast resistor when running a Pertronix or you will fry it. The instructions for the Pertronix state that you need to keep the ballast resistor in the system.

[jgerry2002]

Pertronix for sure needs proper resistance. Whether its an external resistor or a coil with built-in resistance, its pretty clear.

The warm start issue is likely fuel pressure related. You are probably missing the check-valve that keeps fuel from flowing back into the tank. W&N has this part in germany, not sure where else to source it.

[JohnS]

Per the Pertronix documentation sheet that comes with the unit, you need to connect the +12v connection of the Pertronix before the ballast resistor so that it is always supplied with the full voltage. I've been running mine that way along with the stock 1.8 ohm ballast resistor and red coil for years.

[Guest Anonymous]

Based on the posted replies and a telephone conversation with Scott Sislane, the first approach will be to replace the current Bosch Blue coil with a stock OE black coil (from Blunt), that does not have the resistor present in the blue one. Thanks for the help.

_______________________

Roger