MSD Coil replacement

Here's the deal with "hotter" coils. Coils are built with a rev range in mind. The stock coils are meant to provide a great spark from idle to around 5K where they start loosing steam. The MSD Blaster coil is meant to provide a great spark from 2500-6500+ rpm. At idle, the stock coil will provide more spark current than a MSD Blaster will with a stock ECU or points, but will start to pull away in power over 2500 rpm.

This is why multiple discharge boxes like a Mallory or MSD are recommended for use with an aftermarket coil. Under 3K, they send 3 sparks to make up for the coil's underperformance at lower rpm. Not only that, but they also surge the coil with 500-600V on the primary side vs. 12V from a points or stock style Mopar ECU.

On the other side of the coin, this is why dual point distributors were used on hp offerings from the factory as the increased total dwell angle allowed the stock coil more time to charge increasing the stock coils ability to provide a sufficeint spark at higher rpm. What does this mean to you? IMHO, I wouldn't bother replacing the stock coil with an aftermarket coil unless you are using a multiple spark discharge style ignition box. It won't hurt anything but you won't be gaining anything in spark energy below 2500 rpm.

Oh yeah, I want to add that the MSD oil filled coils should be mounted right side up, not on their side. They used to offer an epoxy filled coil that could be mounted in any position, but I don't know if they still do.....Yep they do, it's part number 8222.