MSD HI-Vibration coil and Ballast resistor?
 

Hey again!

I just got my MSD "HI-Vibration" and MSD ballast resistor today! I have a stock ignition system in the 1975 911. I wanted to know if I need to use the MSD ballast resistor with the new MSD Hi-Vibration coil? Or do I just swap out the old leaking Bosch coil with MSD coil w/o ballast resistor?

I see in previous posts that some people use ballast resistor and some don't use them.

Thanks,
Rpettway SmileWavy

The way I understood a previous post by Warren, the coil alone is compatable with the Bosch CD ingition unit...

I just read the MSD papers. The ballast resistor is for current triggered tachs which we don't have. Or engine run-on which you don't have. You have stock ignition which means you have a Bosch or permatune CDI.

Oh I was told that the resistor is to reduce the voltage to extend point life.

Mike

correct on old ignition systems that are not CD. The routine was to run 12v directly to the coil from your ignition sw for starting.. then when the ignition sw is laid to the run position another ignition sw wire goes thru the resistor droping the voltage to around 8v, then to the coil.

you should have stock Bosch or Permatune CD box on your drivers side engine compartment electric panel.. make sure you have this unit installed..

ohhh.. I scrambled who asked the question I answered.. maybe a '72 didn't have a CD.. maybe it has the old induction coil ignition? If so then a resistor is needed.

so sorry

Ron...'72 is Bosch CD...

oh yeah. i should've remembered

"so sorry" ..I take that back :D