My engine is a 59 292 bored .060 with headers, manual T98. The isky cam is 301444 E-4, also Mummert intake.

What is your engine combination?.. If it is another post I could look back. Your camshaft will have a lot to do with what type advance curve you should run.. Hooking your vacuum advance to manifold vacuum kind of skews the situation. You are basically adding probably 20 degrees or more at idle because the vacuum pot will be feeding the engine full advance. Your carb should regulate when the vacuum advance kicks in at cruise,not under power or at idle. Normally on a stock to modest build engines like 12-14 initial advance... No vacuum hooked up  and a total of 36 to 38, No vacuum hooked up..3000 rpm is a rule of thumb for when it is all in, but anywhere from 28 to 36 is fine.  You will never tell the difference in the seat of your pants.  ..

Hey guys so I have been playing with timing since i have installed this new MSD 8383 in my 292. I have been experimenting with the initial timing from 12 to 16. Seems like so many different guys like different initial timing. I am also running full manifold vacuum advance. One thing i dont have my head wrapped around is how fast the distributor advance should be coming in. The attached msd charts show the different springs and their rates. I have the blue stop bushing installed which limits the dizzy advance at 21º . I also have the 2 blue springs installed. At 16º initial that puts me at 37º total. but with the vacuum advance i am not sure when it is dropping off and curious if its overlapping in the dizzy advance. If I should be getting all the advance in before 3000rpm then why on the msd chart does the different springs continue to advance way past 3000?