I posted this a couple of years ago. Still relevant. Rick
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
http://www.hotrodders.com/forum/dist...1-a-59033.html