Re: vacuum advance question
Those valves delay the vacuum from getting through, they don't lower it, just slow it down.
The color on the end of it determines the seconds it delays it.
As I remember, they come in red, green, blue and yellow, black. They range from 5 seconds to 20 or 30? seconds. But not necesarily in that color/seconds order.
They delay the vacuum from going through - like to the advance, but they don't hold it in - so it's one way only like a check valve. Handy to have sometimes.
Yes, it can help with the "tip in". Especially the longer delay ones. But if you are holding the throttle in that spot for longer than the delay, it'll ping again.
Better than nothing though.
Interesting -- 70's Fords used them on their vacuum advance - caused an advance delay - made it stumble on acceleration sometimes.
GM same vintage had a similar stumble - caused by too fast an EGR.
Easy way to cure 2 cars - take the delay valve off the Ford and put it on the GM! Must have done hundreds. Yes, not smog legal, He He - but what smog tech would ever notice it?