Vacuum advance off manifold?

[Tdskip]

Good morning. I have a 2.0L with dual Weber’s without a vacuum port. I am running a vacuum advance SVDA and need to get a vacuum signs going.

Is tapping the intake manifold fair game or best to pull a carb and tap that?

Thanks in advance for the help.

[V8Nate]

The dual idf's don't have much of a vacuum signal in my experience. I tapped each intake runner and brought the hoses to a 5 port vacuum tee. I don't remember what vacuum force is needed for the svda dizzy advance cup is but I don't think you will see much action with dual 2 barrels

[Tdskip]

Thanks for the response Nate, just trying not to leave performance on the table since it's designed to use vacuum advance.

[twodollardoug]

I run dual idf 40s and an svda. You can see the advance working with a timing light. At idle when the butterflies are closed and vacuum is high the timing is way advanced. Then as you open the throttle and vacuum decreases, the timing retards. It is easy to see with your timing light.

That is why we time our engines with the vacuum disconnected or pinch. We don't want the vacuum to fool us when we time for full advance.

[dstar5000]

VACUMN SIG COMES FROM ABOVE THE BUTTERFLY, NOT BELOW IT... USE THE PROPER PORT. IF YOU DONT HAVE IT. MAKE IT,

DON

[V8Nate]

VACUMN SIG COMES FROM ABOVE THE BUTTERFLY, NOT BELOW IT... USE THE PROPER PORT. IF YOU DONT HAVE IT. MAKE IT,

DON

Mmmhmmm

[66brm]

He's right, using manifold vacuum makes the distributor advance at idle and not when you open the throttle. You need the port to be just above the throttle plate at idle/closed so when you crack the throttle then you get the advance

[dstar5000]

VACUMN SIG COMES FROM ABOVE THE BUTTERFLY, NOT BELOW IT... USE THE PROPER PORT. IF YOU DONT HAVE IT. MAKE IT,

DON

Mmmhmmm

The vac port is here, circled in black. This still has the block off screw installed, it would need to be removed.

18950.138f.jpg

Don