Coils: does ground polarity matter?

[John Barry [CLC17027]]

I'm looking to replace the existing coil in my '40 LaSalle (naturally we're talking a 6V positive ground system).  I believe that the nature of the ground (positive vs. negative) doesn't matter with respect to the coil--but could someone please confirm/correct this?  Thanks.

[Dave Shepherd]

Yes polarity on any coil is critical, you can loose about 25% of the maximum out put.