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<x-charset iso-8859-1>Hmm, didn't appear the first time - here goes again... Dave. > > No I left the hose on last time. Jim mentioned that as well, and I checked > > it and I don't think it had vacuum at idle, but I will re-check it to be > > sure. > > > > The only stock Type 3 distributors where timing is done with hose(s) on is > the twin vac on the dual carb (ie the one yours should have). Whether it > makes a difference in every case I don't know, but I can't see why they > would bother to get you to remove the hose if it wasn't desirable. > BTW which vac connection are you using (as there should be 2 to choose > from)? > > Static timing at about 7.5 deg BTDC is generally a good stand-by timing > position; I have assumed that timing with a light at 0 deg (TDC) means the > system somehow has about 7.5 deg ignition retard built in, but maybe I'm > wrong about that. > > An extract from an Australian manual states of the dual vac distributor:- > "At the initial point of starting the chamber connected to the vacuum source > below the closed throttle moves the distributor plate 7° in the direction of > distributor rotation, thus retarding the ignition. When the throttle is > opened connecting the inner vacuum chamber to the vacuum source above the > throttle butterfly, i.e. both chambers subjected to a common vacuum source, > the vacuum to the diaphragm unit is progressively equalised returning the > distributor plate to the original and static timing point. > Further progression of the throttle opening and subsequent increase in > engine rpm causes the centrifugal advance mechanism to come into operation. > The centrifugal advance assembly operates directly on the distributor shaft > cam and independently of the vacuum unit which operates on the distributor > plate only. > > NOTE: The vacuum unit does not advance the ignition timing. It retards the > ignition 7° at idle speed and returns the plate to the static position after > throttle opening." > > There's a bit more to the design, as the two ports have different bores, so > there is a gradual change to the plate position. > > It would be worth watching what happens to the advance using a timing light > as the throttle is gradually opened. Try timing it on 7.5 deg BTDC and > check what the maximum advance ends up at (up to 28 deg is considered fine). > > Dave. > UK VW Type 3 & 4 Club > http://www.hallvw.clara.co.uk/ > ------ > > > ------------------------------------------------ To unsubscribe, E-mail to: <type3-off@vwtype3.org> For more help, see http://vwtype3.org/list/ </x-charset>