[DougD]

Originally Posted by r67cat

Here is one of the best definitive articles on vacuum advance. I converted my 66 428FE from a non vacuum MSD back to a Ford dizzy with a Pertronix ignition and vacuum advance. Unless you are running your car at WOT, you should run vacuum as this article so perfectly explains. You will improve cooling at idle, drivability and plug fouling. Take your information from a power train engineer and not from a backyard hobbyist. Rick Distributor Tuning and Theory - Part 1 - Hot Rod Forum : Hotrodders Bulletin Board

r67cat
Thanks for posting that article. I've read it before, and I think it's the simplest, best-written primer on vacuum advance that I've seen. I intend to change out my MSD dist for exactly the reasons detailed in the article. I plan to do some testing on my engine to determine what it has for manifold vacuum at idle, and then tune the vacuum can on the Duraspark to work properly. The article states that I should set up the vacuum advance to work at around 2 inches of vacuum less than the engine has at idle, so I'll start there. It is my understanding that there is an adjustment inside the vacuum canister of the Duraspark, so hopefully I can make changes to suit my particular combination.
Doug