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On Wed, 2002-05-15 at 11:30, Jim Adney wrote: > On 15 May 2002, at 9:15, Everett Barnes wrote: > > > The initial advance drops to 7.5 BTDC when I take the vacuum hose off. > > I also sucked on the vacuum hose to check for smooth advance. > > > > The advance worked on my workbench, it just didn't fully return to its starting > > position. I could push it a few more degrees with my finger. Now that it is > > installed and running, it seems to be working fine. > > If it always sticks in the same place your timing will always appear to be fine. > > Suppose it has a total advance of 10 degrees (20 crankshaft degrees) but it > sticks at 2 degrees (4 crankshaft degrees) when it drops back. Then when > you time it you're really already 4 degrrees up the advance curve, assuming > that it's dropped back to it's "usual" sticky spot. In this case you only get 16 > degrees of additional advance (plus your 7.5 deg of static advance) that's > 23.5 deg instead of 27.5 deg. This is a SIGNIFICANT difference, from only 2 > deg of stickyness. > > You should open up the dist, suck on the vacuum adv hose and release it. > Then try to push the points plate back home. If it moves some more, then > you probably aren't getting as much out of it as you should. > In a distributor for carb engines, the spring tension for the vacuum advance is adjustable. The pin in the dist. body that the spring attaches to is an excentric. If you turn that pin, you will loosen/tighten the spring. There is a special tool to do this with, if needed. Some of the earlier distributors, have 2 springs in them. I have a 311-905-205E dist. that has a spring above and below the plate. -- Russ Wolfe '66 FB MT (It drove) '71 FB AT '65 Bug (not running) russw@classicvw.org http://www.classicvw.org ------------------------------------------------------------------- List info at http://www.vwtype3.org/list or mailto:help@vwtype3.org