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Thanks very much for the graph Dave- I really appreciate having some solid specs to work with. I double checked and mine is the AJ dizzy. I hope you don't mind but I put the graph up here: www.mo-sys.com/1973_distrib_p2.gif Comparing it to my graph I see a few significant differences. My total mech advance is a bit higher but you're right that the springs will surely have weakened over time. I expected to see a step in the mech graph too as when I had my dizzy apart I saw that one of the springs was a little longer than the other as if it were meant to advance faster at first then catch up to the second spring and slow down a bit. That kink happens at 1400 rpm on my dizzy at 16 deg adv, and 1500 rpm on the specs at 12 deg adv ( a difference of 4 deg.). Also I get 32 deg mech adv at 3500 whilst the specs say I should have 26 at 3500 (a difference of 6 deg). So maybe I should just retime at say 2 deg advance at idle to take care of that offset? (instead of 7.5) As for the vac advance there are more significant differences. The VW graph shows that at 10cmHg I should be about half way through the advance at 6deg- on my graph I'm only just starting at about 3 or 4 deg. Mine maxes out in the 20-25 cmHg range where it should do at about 12cm Hg. I don't know the accuracy of my vac gauge and will try to get a better one to re-do the test, but this seems way out- actually the opposite of what I originally thought. Maybe the diaphragm has stiffened up with age and is causing that slower response. The part number for the vac can given on the first page of that bulletin is 311 905 271 F. All I could find on mine was the number 507 stamped on the arm so maybe its not the right can. Mark Seaton, '73 Fasty London ----- Original Message ----- From: "Dave Hall" <dave@hallvw.clara.co.uk> > That agrees with the charts on their way to Mark. Centrifugal advance quotes > 24-28 crankshaft degrees at 3800 (in fact it levels out at 1900), and vacuum > advance is 8-12 degrees, giving a possible 40 (crankshaft) degrees of advance, > including the 7.5 degrees at idle rpm. This is for the 311 905 205 AJ single > vacuum distributor for the 1973 twin carb engine. The graphs of course show > distributor degrees. > > Max centrifugal is given as 14 distributor degrees (28 crankshaft) so maybe your > springs are a bit weaker than they should be - must be getting old. > > 850rpm is fine for manual. > > Dave. > ------ > ----- Original Message ----- > From: "Mark Seaton" <Markse@mo-sys.com> > > > Jim (and anyone else interested) here are my advance curves for the car > > stationary: > > > > www.mo-sys.com/mark_eng_adv_curves.pdf ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org