Vacuum advance

[Wildfire]

I have just noticed that the Vacuum advance on my dizzy is connected to, um nothing. Is this bad? O r will it not really make much difference. Should I block it off?

[shadowfax]

If that's the pipe that goes to the rocker box cover, with a small plazzy cylinder in the middle of the two soft rubber pipes that link the dizzy to the rocker box cover - which Bluey's has still present - then I believe it makes no odds whether it's on or off.

But I, erm, could be wrong

[Boosted Ls1]

The vac advance pipe from the dizzy should connect to a small nipple on the plenum just above and before the throttle blade unless I'm missing something Bet you have an air leak if the nipple hasn't been blanked off.

Boosted.

[Wildfire]

I don't have a nipple on the car as I have the Tripple Throttle bodies and Carbon Plenum. Just wondering if it will make any difference if I find somewhere to connect it to. I know my mini runs like poo if I disconnect the Vacuum advance.

[red griff 500]

The vacuum advance on mine advances the ignition very very slowly under constant throttle conditions - it does this by means of a one-way flow restrictor in-line with the flexible pipe between the Plenum inlet and dizzy. I believe that it is to improve economy at steady throttle. Yours might be different - they dont all have the restrictor.

[steve-v8s]

Never really thought about this before but is it actually a vacuum advance or vacuum retard ? Would have thought that the negative pressure is at it’s greatest with the throttle closed. The engine will be trying to suck in air and the flow will be restricted making I would have thought negative pressure. May be wrong on this but would think the ignition timing needs to be advanced at higher revs and load and retarded at low revs.