scorreia Posted July 15, 2004 Share Posted July 15, 2004 74 260Z. Weber 32/36 DGV's. I just adjusted the timing and the Datsun manual said 8 degrees, but it idled better around 10. It was running decently (stumble around 2000rpm but idled and revved fine) so I replaced the PCV valve, and now it is running rich. Very rich. Large amount of smoke out the tailpipe at idle. Plugging the PCV valve while the engine is running seems to have no effect at all. Other related info: The vacuum advance diaphragm is broken. I pulled the line which leads to the front carb and sucked on it but nothing in the distributor moved. Not sure if this is related to my problem or not. I have read the vacuum advance isn't really necessary so I think not. The rear carburetor has vacuum (attached to the servo diaphragm), but makes a strange sucking noise. I don't know what to think about that one. I tried adjusting the idle mixture screw but nothing helped. I am around 3 turns out right now, so I may need to switch to a smaller jet but it shouldn't be running this rich, should it? Also, the air pump (smog pump) is not attached. Well it's attached but there is no belt turning it. It's been like that for quite some time, should I hook it back up? I haven't driven the car in 4 years, and some generic mechanic installed the carbs and adjusted everything and I am beginning to think he didn't do it correctly. I am trying to figure this all out, so be patient, I am learning. I am also looking for an online vacuum diagram, something doesn't seem right with where these lines are going and I just want to double check everything. Anyone got a link? Quote Link to comment Share on other sites More sharing options...
scorreia Posted July 15, 2004 Author Share Posted July 15, 2004 Update. I checked the distributor, and it appears that the part that is supposed to rotate for the vacuum advance (if the diaphragm was working) was stuck in the middle somewhere so I rotated it back and it appears much happier. Still a bit of smoke when I rev it but not the constant stream. It idles well and no 2000rpm stumble anymore. Much better. Now I will just replace the distributor and the diaphragm and all should be well. Quote Link to comment Share on other sites More sharing options...
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