When does vacuum advance kick in?

I think AJ/formS is running around of 51 degrees total of mechanical, vacuum, and dashboard controlled timing advance at highway speed in a 367 inch 340. Sounds extreme until you see some of the smog era EGR distributors that have upwards of over 60 degrees of combined advance at cruise RPM.

Naw. If you read the MP engine manual it clearly says it's not uncommon to see 60* or more including vacuum advance at part throttle. So it's really not extreme at all. It's just that most people don't read the MP books at all. LOL