#1 S1 vacuum for 123 Ignition
Posted: Mon Jan 12, 2026 12:49 pm
I would like to use manifold vacuum for my 123+, but searching here and far ( google ) I can't find a conclusive thread that directs to the ideal location of a tapping for the vacuum take off on an S1 4.2 manifold.
I know the ported system on the HD8 at idle can be ignored on the 123 by using the " Ignore MAP below rpm '' setting, but once the throttle is open, is the vacuum generated a good source for genuine useful manifold pressure?, if it is then there seems little point in using pure manifold vacuum.
Be interesting to hear thoughts, I may not be that good at searching, but I have found some really long threads on the subject.
I know the ported system on the HD8 at idle can be ignored on the 123 by using the " Ignore MAP below rpm '' setting, but once the throttle is open, is the vacuum generated a good source for genuine useful manifold pressure?, if it is then there seems little point in using pure manifold vacuum.
Be interesting to hear thoughts, I may not be that good at searching, but I have found some really long threads on the subject.