Just some guy
Join Date: Jun 2001
Location: SC foothills, USA
Durasparks are well proven by literally over a million Fords that left the factory with them. For your basic electronic ignition, they work fine. And if we stop fooling ourselves, provide all the ignition most of us will ever need. The distributors are tunable, Summit sells lighter advance weight springs, there's a website about tailoring the advance curve simply by swapping around the advance weights, and you can even get adjustable vacuum advance cans. A nice plus is that Duraspark replacement parts on the shelves of about any parts store you care to visit. They get along just fine with hi-po ignition coils.
There are some downsides. Used distributors tend to have worn bushings and the advance weights tend to seize because no one ever lubes them (they do have provision for this). And of course they've been out of production for quite some time. Rebuilt distributors are readily available though. Many folks think the Duraspark distributors are too large and unattractive. New control boxes are widely available, the cheaper ones have a bad reputation though. It's sometimes said to be best to buy them two at a time so to have a backup.
MSD boxes ARE better. They provide multiple sparks at low rpm's and stronger spark at higher rpms. There are options like boost retard for turbo cars and other stuff a Duraspark isn't capable of. They have also been know to fail, racers usually keep a spare, the majority of folks have good luck with them though.
MSD distributors are: brand new, made for high performance duty, nice looking, built of better materials and to a higher quality level.
Most MSD boxes get along just fine with a Duraspark distributor when you buy the inexpensive adapter.
.... it wouldn't be the first time reality took theory and conjecture out behind the woodshed and gave them a good thrashing.