Vacuum advance information and myths

440 Mike said
OK, so what I gather is that when vacuum advance is connected to PV the only time it comes into play is under light throttle cruise conditions. When vacuum advance is connected to MV it comes into play when under light throttle cruise conditions and at idle.

So how does the advanced timing at idle effect combustion, heat, and performance?

Read the link that Mattax posted above. He covers all that and more.

One interesting note is he talks about cam timing and compression ratio and why it matters.

As I’ve said, if you have to add a bunch of timing with MV/VA you have other issues.