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MSD Ballast Resistor needed?


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Hi, 

 

 

I had to replace my broken stock coil and went with the MSD 8202 Blaster 2 coil. Now my question: Do I need the 0.8Ohm resistor or not? 

It runs fine, but the tach reading is not very stable on low RPMs and it drops towards 0 everytime the turn signals flash. Might be another reason though :)

I have the 79-80 distributor with the E12-80 electronic ignition module. 

 

Thank you!

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Thank you, here is what I found on the MSD website:

 

Primary resistance .7 OHMs Secondary resistance 4.5K OHMs

 

I drove already a few hundred miles with the wrong resistance, does that damage anything or what can happen?

 

Do you have any idea what could trigger the turn signal behavior?

 

Thanks for your input!!

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That resistance is probably fine.  The E12-80 module has current control, I believe, it can handle it.  

 

The tach needle problem might just be a tach problem.  Check the capacitor/condenser by the coil wiring.  The tachs don't like electrical noise and the condenser is there to damp it.

 

You haven't said what year car you're working with.

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I've solved a twitchy tach needle on my 76 by adding a condenser to the negative side of the coil.  It was a plain old alternator type, connected to the negative post.  

 

The early tachs are designed for the 6-volt system, with the coil and ballast resistor.  The later electronic modules might just be too noisy for the early tachs.  I'm not an electronics expert but I know that it worked for me, with a GM HEI module (the problem came back one day when the condenser/capacitor wire broke due to vibration), and it can't really hurt anything.

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I have a new Speedhut Tach, so it must be a wiring/condenser issue.

 

This changes the situation.  But, still, a condenser won't hurt.  You might check your grounds and various connections too.

 

Also consider just a low battery and/or weak alternator affecting the ignition system.  The turn signals draw extra current and the Z alternators are known to be close to maxed-out at idle speed.  Try revving the engine with the turn signals on and see if the dying needle fixes itself.

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