Thread: vac advance?

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1971-307 should vac. advance have vacume at idle,or only on eccelaration? Edelbrock 2101 performer with 1406 carb.carb has two small vac. ports on front of it,one hase no vac. at idle the other does.not sure the one to use.

Depends on which one the car likes---Heavy car with the small engine would probably run better with unported vacuum--also depends on how well, how soon, and how much advance the mechanical throws in......

If you're using the stock distributor, use the full time vacuum - on the right (driver's side)...

In stock form, they used the progressive port. Must people use the full manifold vac now.

I use manifold vacuum,be sure the mechanical advance is in good working order along with the vacuum advance. I then set my timing to 36 dgrees @ 3200 rpm (in other words full advance)
If you do it like this the timing will retard on acceleration (or load) and will usually keep it from spark knocking on the fuel we have nowdays. This seems to work well on any older car or hotrod.