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Subject: [T3] 72 FI timing question > > What is the timing supposed to be set to? (with vacuum hoses off, > idle speed adjusted properly) > > The sticker ON THE ENGINE (original, from VW) says 5 degrees > A.T.D.C. There used to be a separate sticker with a picture of the > pulley, but this has disappeared. > > Bentley, and Without Guesswork say 5 deg B.T.D.C. and have > pictures that are consistent with this. > > If I study the distributor advance curves carefully I find that it > appears that all the advance graphs are given in distributor shaft > degrees and RPM, while the chart for the 72 cars appears to be in > crankshaft degrees and RPM. If I compare the 72 and 73 data > presented there, it looks like all this is consistent with timing both > to 5 deg BTDC. > > I have not checked my Haynes. I also need to look in the owner's > manual to see if it has anything about this. > > Everything about this appears to indicate that the factory sticker is > just wrong. The only thing I can think of is that either VW meant > something different by the A in ATDC (like Ahead, or Advanced) or > that it was just a bonehead mistake. This engine came out of a > VERY early 72 production car, so I wonder if it is possible that VW > corrected this mistake later. > > I'd love to move the timing from 5 deg BTDC to 5 deg ATDC as this > would make for much better power and fuel economy, but this is > such a big change that I'm reluctant to make it unless I'm sure that > it won't damage something. The only way it could hurt something > would be if I'm wrong about the 72 distributor charts in the Bentley > manual being in crankshaft degrees and RPM. If I have to double all > of these numbers, then this would result in too much advance. > > Russ, do you remember what you timed them to? The 72-3 pulleys > have marks | | | |, which are at -5,0,5,7.5. Is the correct mark > the left mark or the 3rd from the left? > My Chilton's says 5 BTDC hoses off. I checked with a couple other older VW mechanics and they say 5 BTDC hoses off. But I think you will find that if you set it there, and then put the "retard" hose on the distributor, it will come out to be about 5 ATDC. The retard side of the distributor was to get the car to meet CA emission spec's at idle. Russ Wolfe russw@classicvw.org http://www.classicvw.org/ ------------------------------------------------------------------- Too much? Digest! mailto:type3-d-request@vwtype3.org Subj=subscribe