[Excaliber]

MSD says flat out they use heavy springs to retard/slow down the mechanical advance on their distributors when shipped new. That's what I would do if I was them! Maximum protection from detonation for those who don't know what they want and yet easy to change the advance curve and advance limit for those that do.

By the way, thanks Tom for your thread on reading spark plugs. An interesting approach but potentially fraught with some downfalls. The new gasolines make reading the plugs tricky, at best. Also MSD says because of the mulitiple spark with the box units it is difficult to rely on plug reading alone. It's getting tougher and tougher for a backyard kind of tuneup these days! Still good basic advice on plug reading that certainly has it's place.