I find info and part#s on vacuum delay valves which delay the release of vacuum... such as for timing advance or other, keeping vacuum to the component for a short time after the source is expired.

I want one which works opposite... a valve to delay the application of vacuum, but release immediately.

Is there a such thing? If so, please help. This is upon request for a Mercury. What it really needs is to delay the advance on the dizzy, so advice on that would be helpful too. I'm not too keen on weights/springs changes cause/effect.
edit: stiffer springs?